Add support for Cool

This change includes a brief (non-sensical) sample program I wrote to
illustrate many of Cool's language constructs, as well as a simple rule
to distinguish Cool files from Common Lisp or OpenCL (it has a line that
starts with the word 'class'). Further, it includes a second example
program adapted from an example contained in the Cool distribution
(list.cl), which contains a few further language constructs and captures
the style of a Cool program.

samples/Cool/list.cl

@@ -0,0 +1,26 @@
+(* This simple example of a list class is adapted from an example in the
+   Cool distribution. *)
+
+class List {
+   isNil() : Bool { true };
+   head()  : Int { { abort(); 0; } };
+   tail()  : List { { abort(); self; } };
+   cons(i : Int) : List {
+      (new Cons).init(i, self)
+   };
+};
+
+class Cons inherits List {
+   car : Int;	-- The element in this list cell
+   cdr : List;	-- The rest of the list
+   isNil() : Bool { false };
+   head()  : Int { car };
+   tail()  : List { cdr };
+   init(i : Int, rest : List) : List {
+      {
+	 car <- i;
+	 cdr <- rest;
+	 self;
+      }
+   };
+};