Additional Fourslash functionality for retyper scenarios
Misc bug fixes
Fixes build errors when running fourslash tests
Pull LS updates for quickInfo
Declaration comments of accessors shouldnt be emitted when not using -c option
Move over to an immutable representation of a host document (called IScriptSnapshot).

This representation ensures that it is observably immutable.  features can thus
hold onto instances without having to worry about the data changing underneath them.
This is important for the parser as it created tokens which point back at the document
to save space.  Prior to this change it was possible to observe the document changing
which broke all sorts of invariants.

This also vastly simplifies much of our code as it removes at least three unnecessary
wrappers for the host document.
Recover correctly from a failed test
Merge branch 'develop-0.9.x' of https://git01.codeplex.com/typescript into develop-0.9.x
Fixed stack overflow in case of array type tostring
Merge branch 'develop-0.9.x' of https://git01.codeplex.com/typescript into develop-0.9.x
Move all the new parser code under the 'TypeScript' module.

Also fix null ref exception when converting from SyntaxTrees to ASTs.