better regex for matching emacs modeline

the emacs modeline is actually a per-file variable setting mechanism, which means it can have other flags in it.

this regex extracts the part that corresponds to the file's language ("mode:" - ie emacs major mode)

http://ergoemacs.org/emacs_manual/emacs/Specifying-File-Variables.html

lib/linguist/strategy/modeline.rb

@@ -1,7 +1,7 @@
 module Linguist
   module Strategy
     class Modeline
-      EmacsModeline = /-\*-\s*mode:\s*(\w+);?\s*-\*-/i
+      EmacsModeline = /-\*-\s*((?!mode)[\w-]+\s*:\s*([\w+-]+)\s*;?\s*)?(mode\s*:)?\s*([\w+-]+)\s*;?\s*((?!mode)[\w-]+\s*:\s*([\w+-]+)\s*;?\s*)?-\*-/i
       VimModeline = /\/\*\s*vim:\s*set\s*(?:ft|filetype)=(\w+):\s*\*\//i
 
       # Public: Detects language based on Vim and Emacs modelines
@@ -22,8 +22,13 @@ module Linguist
       #
       # Returns a String or nil
       def self.modeline(data)
-        match = data.match(EmacsModeline) || data.match(VimModeline)
-        match[1] if match
+        match = data.match(EmacsModeline)
+        if match
+          match[4]
+        else
+          match = data.match(VimModeline)
+          match[1] if match
+        end
       end
     end
   end