* Removed the scanless parsing feature (dynamic lexing is king)
* Default LALR lexer is now contextual

- @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.

(inspired by issue #116)

- Reasoning addressed in Issue #116
- Renamed example and grammars file to use new extension.
- Changed `.g` to new extension of `.lrk` in places where it is
  referenced.

It now knows how to resolve ambiguity! And in a memory-efficient way!

Definitely needs more work though