syntax: 'var'->'let' 'function'->'func'

- 'var' has some weird scoping connotations with users of JS. better to change it to 'let', which will decide whether to make the variable a local or a global
- 'func' looks visually appealing lol
- some minor refactoring done in cparse.c

examples/test.cosmo

@@ -1,10 +1,10 @@
 // crafts a dummy proto
 proto test 
-    function __init(self) end
+    func __init(self) end
 end
 
 // instance of test
-var obj = test()
+let obj = test()
 
 test.__index = function(self, key)
     print("__index called!")