Merge branch 'refactor-heuristics' into 1036-local

* refactor-heuristics: (43 commits)
  update docs
  Clean up heuristic logic
  Allow disambiguate to return an Array
  Rename .create to .disambiguate
  docs
  Remove inactive heuristics
  Refactor heuristics
  Not going back
  docs
  Move call method into existing Classifier class
  Try strategies until one language is returned
  Remove unneded empty blob check
  Add F# and GLSL samples.  Add Forth and GLSL extension .fs. Add heuristic to disambiguate between F#, Forth, and GLSL.
  byebug requires ruby 2.0
  Remove test for removed extension
  Fix typo in test
  add rake interpreter
  add python3 interpreter
  Remove old wrong_shebang.rb sample
  Add byebug
  ...

Conflicts:
	lib/linguist/heuristics.rb
	test/test_heuristics.rb

samples/F#/sample.fs

@@ -0,0 +1,15 @@
+module Sample
+
+open System
+
+type Foo =
+    {
+        Bar : string
+    }
+
+type Baz = interface end
+
+let Sample1(xs : int list) : string =
+    xs
+    |> List.map (fun x -> string x)
+    |> String.concat ","

samples/Forth/core.fs

@@ -0,0 +1,252 @@
+: immediate   lastxt @ dup c@ negate swap c! ;
+
+: \   source nip >in ! ; immediate \ Copyright 2004, 2012 Lars Brinkhoff
+
+: char \ ( "word" -- char )
+    bl-word here 1+ c@ ;
+
+: ahead  here 0 , ;
+
+: resolve   here swap ! ;
+
+: '   bl-word here find 0branch [ ahead ] exit [ resolve ] 0 ;
+
+: postpone-nonimmediate   [ ' literal , ' compile, ] literal , ;
+
+: create   dovariable_code header, reveal ;
+
+create postponers
+    ' postpone-nonimmediate ,
+    ' abort ,
+    ' , ,
+
+: word \ ( char "<chars>string<char>" -- caddr )
+    drop bl-word here ;
+
+: postpone \ ( C: "word" -- )
+    bl word find 1+ cells  postponers + @ execute ; immediate
+
+: unresolved \ ( C: "word" -- orig )
+    postpone postpone  postpone ahead ; immediate
+
+: chars \ ( n1 -- n2 )
+    ;
+
+: else \ ( -- ) ( C: orig1 -- orig2 )
+    unresolved branch swap resolve ; immediate
+
+: if \ ( flag -- ) ( C: -- orig )
+    unresolved 0branch ; immediate
+
+: then \ ( -- ) ( C: orig -- )
+    resolve ; immediate
+
+: [char] \ ( "word" -- )
+    char  postpone literal ; immediate
+
+: (does>)   lastxt @ dodoes_code over >code ! r> swap >does ! ;
+
+: does>   postpone (does>) ; immediate
+
+: begin \ ( -- ) ( C: -- dest )
+    here ; immediate
+
+: while \ ( x -- ) ( C: dest -- orig dest )
+    unresolved 0branch swap ; immediate
+
+: repeat \ ( -- ) ( C: orig dest -- )
+    postpone branch ,  resolve ; immediate
+
+: until \ ( x -- ) ( C: dest -- )
+    postpone 0branch , ; immediate
+
+: recurse   lastxt @ compile, ; immediate
+
+: pad \ ( -- addr )
+    here 1024 + ;
+
+: parse \ ( char "string<char>" -- addr n )
+    pad >r  begin
+	source? if <source 2dup <> else 0 0 then
+    while
+	r@ c!  r> 1+ >r
+    repeat  2drop  pad r> over - ;
+
+: ( \ ( "string<paren>" -- )
+    [ char ) ] literal parse 2drop ; immediate
+    \ TODO: If necessary, refill and keep parsing.
+
+: string, ( addr n -- )
+    here over allot align  swap cmove ;
+
+: (s") ( -- addr n ) ( R: ret1 -- ret2 )
+    r> dup @ swap cell+ 2dup + aligned >r swap ;
+
+create squote   128 allot
+
+: s" ( "string<quote>" -- addr n )
+    state @ if
+	postpone (s")  [char] " parse  dup ,  string,
+    else
+	[char] " parse  >r squote r@ cmove  squote r>
+    then ; immediate
+
+: (abort") ( ... addr n -- ) ( R: ... -- )
+    cr type cr abort ;
+
+: abort" ( ... x "string<quote>" -- ) ( R: ... -- )
+    postpone if  postpone s"  postpone (abort")  postpone then ; immediate
+
+\ ----------------------------------------------------------------------
+
+( Core words. )
+
+\ TODO: #
+\ TODO: #>
+\ TODO: #s
+
+: and  ( x y -- x&y )   nand invert ;
+
+: *   1 2>r 0 swap begin r@ while
+         r> r> swap 2dup dup + 2>r and if swap over + swap then dup +
+      repeat r> r> 2drop drop ;
+
+\ TODO: */mod
+
+: +loop ( -- ) ( C: nest-sys -- )
+    postpone (+loop)  postpone 0branch  ,  postpone unloop ; immediate
+
+: space   bl emit ;
+
+: ?.-  dup 0 < if [char] - emit negate then ;
+
+: digit   [char] 0 + emit ;
+
+: (.)   base @ /mod  ?dup if recurse then  digit ;
+
+: ." ( "string<quote>" -- )   postpone s"  postpone type ; immediate
+
+: . ( x -- )   ?.- (.) space ;
+
+: postpone-number ( caddr -- )
+    0 0 rot count >number dup 0= if
+	2drop nip
+	postpone (literal)  postpone (literal)  postpone ,
+	postpone literal  postpone ,
+    else
+	." Undefined: " type cr abort
+    then ;
+
+' postpone-number  postponers cell+  !
+
+: / ( x y -- x/y )   /mod nip ;
+
+: 0< ( n -- flag )   0 < ;
+
+: 1- ( n -- n-1 )   -1 + ;
+
+: 2! ( x1 x2 addr -- )   swap over ! cell+ ! ;
+
+: 2* ( n -- 2n )   dup + ;
+
+\ Kernel: 2/
+
+: 2@ ( addr -- x1 x2 )   dup cell+ @ swap @ ;
+
+\ Kernel: 2drop
+\ Kernel: 2dup
+
+\ TODO: 2over ( x1 x2 x3 x4 -- x1 x2 x3 x4 x1 x2 )
+\           3 pick 3 pick ;
+
+\ TODO: 2swap
+
+\ TODO: <#
+
+: abs ( n -- |n| )
+    dup 0< if negate then ;
+
+\ TODO: accept
+
+: c, ( n -- )
+    here c!  1 chars allot ;
+
+: char+ ( n1 -- n2 )
+    1+ ;
+
+: constant   create , does> @ ;
+
+: decimal ( -- )
+    10 base ! ;
+
+: depth ( -- n )
+    data_stack 100 cells +  'SP @  - /cell /  2 - ;
+
+: do ( n1 n2 -- ) ( R: -- loop-sys ) ( C: -- do-sys )
+    postpone 2>r  here ; immediate
+
+\ TODO: environment?
+\ TODO: evaluate
+\ TODO: fill
+\ TODO: fm/mod )
+\ TODO: hold
+
+: j ( -- x1 ) ( R: x1 x2 x3 -- x1 x2 x3 )
+    'RP @ 3 cells + @ ;
+
+\ TODO: leave
+
+: loop ( -- ) ( C: nest-sys -- )
+    postpone 1  postpone (+loop)
+    postpone 0branch  ,
+    postpone unloop ; immediate
+
+: lshift   begin ?dup while 1- swap dup + swap repeat ;
+
+: rshift   1 begin over while dup + swap 1- swap repeat nip
+           2>r 0 1 begin r@ while
+              r> r> 2dup swap dup + 2>r and if swap over + swap then dup +
+           repeat r> r> 2drop drop ;
+
+: max ( x y -- max[x,y] )
+    2dup > if drop else nip then ;
+
+\ Kernel: min
+\ TODO:   mod
+\ TODO:   move
+
+: (quit) ( R: ... -- )
+    return_stack 100 cells + 'RP !
+    0 'source-id !  tib ''source !  #tib ''#source !
+    postpone [
+    begin
+	refill
+    while
+	interpret  state @ 0= if ." ok" cr then
+    repeat
+    bye ;
+
+' (quit)  ' quit >body cell+  !
+
+\ TODO: s>d
+\ TODO: sign
+\ TODO: sm/rem
+
+: spaces ( n -- )
+    0 do space loop ;
+
+\ TODO: u.
+
+: signbit ( -- n )   -1 1 rshift invert ;
+
+: xor ( x y -- x^y )    2dup nand >r r@ nand swap r> nand nand ;
+
+: u<  ( x y -- flag )  signbit xor swap signbit xor > ;
+
+\ TODO: um/mod
+
+: variable ( "word" -- )
+    create /cell allot ;
+
+: ['] \ ( C: "word" -- )
+    ' postpone literal ; immediate

samples/GLSL/recurse1.fs

@@ -0,0 +1,48 @@
+#version 330 core
+
+// cross-unit recursion
+
+void main() {}
+
+// two-level recursion
+
+float cbar(int);
+
+void cfoo(float)
+{
+	cbar(2);
+}
+
+// four-level, out of order
+
+void CB();
+void CD();
+void CA() { CB(); }
+void CC() { CD(); }
+
+// high degree
+
+void CBT();
+void CDT();
+void CAT() { CBT(); CBT(); CBT(); }
+void CCT() { CDT(); CDT(); CBT(); }
+
+// not recursive
+
+void norA() {}
+void norB() { norA(); }
+void norC() { norA(); }
+void norD() { norA(); }
+void norE() { norB(); }
+void norF() { norB(); }
+void norG() { norE(); }
+void norH() { norE(); }
+void norI() { norE(); }
+
+// not recursive, but with a call leading into a cycle if ignoring direction
+
+void norcA() { }
+void norcB() { norcA(); }
+void norcC() { norcB(); }
+void norcD() { norcC(); norcB(); } // head of cycle
+void norcE() { norcD(); } // lead into cycle

samples/Ruby/wrong_shebang.rb

@@ -1,2 +0,0 @@
-#!/usr/bin/env python
-puts "Not Python"