refactor

progress so far on refactor to support background parsing
- Background parsing works
- Syntax highlighting works
- Outlining works
refactor

refactoring intellisense to support multi-document intellisense and
caching
Merge branch 'lexer' into importing
wiring up

got the basic flow for completion wired up, just need to implement the
cache and port the value providers.
intellisense cache

initial implementation for intellisense cache, but it's kind of crappy
migrate old code

convert old context providers to implement new interfaces. right now
it's very "dumb" in that it just returns all items right now and doesn't
limit by position
better import parsing

split sass import and standard css import
various fixes
cleanup and fixes

cleanup old documents.
fix intellisense
Merge remote-tracking branch 'origin/importing' into lexer