Remove lookahead2

https://code.google.com/p/esprima/issues/detail?id=523
Linear comment attachment.

https://code.google.com/p/esprima/issues/detail?id=522
Mention Nashorn support.

https://code.google.com/p/esprima/issues/detail?id=524
Library regression test should not use prettified baseline.

As suggested by Bei Zhang, the JSON version of the syntax tree and
the tokens consume less space when it is not indented.

https://code.google.com/p/esprima/issues/detail?id=509
Utilize gc() for V8 and SpiderMonkey

https://code.google.com/p/esprima/issues/detail?id=529
Automatically rewritten for npm.