LESS: Re-instate broken code

Reverts commenting out; does not compile.
Next commit will fix compilation errors for clean diffs.
LESS: Fix compilation errors from new LESS APIs

Does not work yet
LESS: Fix selector expansion for new syntax tree

Because of nested media queries :smile:, we need to look for more
parents.
LESS: Fix DependencyGraph

All tests pass
LESS: Remove old edges when parsing files

Remove dependencies when @imports are deleted.
Also ignore imported URLs.

Includes test cases.
Margin: Fix width persistence
SCSS: Enable compilation chaining
Code: Fix grammar in DontWait() messages

See XML doc comment for correct grammar
Merge pull request #700 from SLaks/less-ctp2-fixes

Fix remaining LESS/SCSS tooling for Update 2 CTP 2