Fennel support (#880)

* Added Fennel support

Created a test file and added support in languages.json

* Updated Fennel test case

Input the wrong number of lines oops

* Corrected the number of comment lines

I am very bad at counting

* Added multiline strings to the test case

languages.json

@@ -139,6 +139,11 @@
       "env": ["elvish"],
       "extensions": ["elv"]
     },
+    "Fennel" : {
+      "line_comment": [";", ";;"],
+      "quotes": [["\\\"", "\\\""]],
+      "extensions": ["fnl"]
+    },
     "Fish": {
       "shebangs": ["#!/bin/fish"],
       "line_comment": ["#"],

tests/data/fennel.fnl

@@ -0,0 +1,18 @@
+;; 18 lines 8 code 5 comments 5 blanks
+
+; this is a ; single comment
+;;;; this is also a single comment ;;;;;;
+
+                  ; "this is a comment too!"
+
+(local variable "I ;am a ;variable!")
+
+; (print "\"I am commented out!\"")
+(print "\"Hello world!\"") ; this is an ; end of line comment
+(print "This is not a comment: ;")
+(print "This is a
+  multiline string")
+
+(fn somefn [x]
+  (print "I am some function.")
+  (print "My parameter is " (string.format "\"%s\"" x)))