Resolved upstream changes to use new file-extension

- @erezsh added the new Lark reference and some other things using the
  current .g extension, so I wanted to resolve them for PR #117
- Renamed lark.g to lark.lark.
- Changed lark_grammar.py to use .lark file extensions.
- Changed urls that used .g to use .lark.

docs/json_tutorial.md

@@ -79,7 +79,7 @@ By the way, if you're curious what these terminals signify, they are roughly equ
 
 Lark will accept this, if you really want to complicate your life :)
 
-(You can find the original definitions in [common.g](/lark/grammars/common.g).)
+(You can find the original definitions in [common.lark](/lark/grammars/common.lark).)
 
 Notice that terminals are written in UPPER-CASE, while rules are written in lower-case.
 I'll touch more on the differences between rules and terminals later.

examples/README.md

@@ -7,7 +7,7 @@
 - [indented\_tree.py](indented\_tree.py) - A demonstration of parsing indentation ("whitespace significant" language)
 - [fruitflies.py](fruitflies.py) - A demonstration of ambiguity
 - [turtle\_dsl.py](turtle_dsl.py) - Implements a LOGO-like toy language for Python's turtle, with interpreter.
-- [lark\_grammar.py](lark_grammar.py) + [lark.g](lark.g) - A reference implementation of the Lark grammar (using LALR(1) + standard lexer)
+- [lark\_grammar.py](lark_grammar.py) + [lark.lark](lark.lark) - A reference implementation of the Lark grammar (using LALR(1) + standard lexer)
 
 ### Advanced
 

examples/lark_grammar.py

@@ -1,12 +1,12 @@
 from lark import Lark
 
-parser = Lark(open('examples/lark.g'), parser="lalr")
+parser = Lark(open('examples/lark.lark'), parser="lalr")
 
 grammar_files = [
-    'examples/python2.g',
-    'examples/python3.g',
-    'examples/lark.g',
-    'lark/grammars/common.g',
+    'examples/python2.lark',
+    'examples/python3.lark',
+    'examples/lark.lark',
+    'lark/grammars/common.lark',
 ]
 
 def test():