Some random cleanup

Review URL: https://github.com/google/traceur-compiler/pull/481

Closes #481.
Refactor ModuleTransformer

This is to make it easier to subclass and override what code to generate.

See issue #461 for motivation.

Review URL: https://github.com/google/traceur-compiler/pull/482

Closes #482.
Extended types annotations

Type annotations work on function declarations & expressions, formal parameters, class members.

Fixes #463

Review URL: https://github.com/google/traceur-compiler/pull/480

Closes #480, closes #463.
Merge branch 'master' into cover-initialiser

Conflicts:
	bin/traceur.js
	src/codegeneration/DefaultParametersTransformer.js
	src/outputgeneration/ParseTreeWriter.js
	src/syntax/Parser.js