DepthTagger calls LanguageService always asynchronously
DocumentEventsListener and DepthTagger cleanup
Merge pull request #260 from vasily-kirichenko/depth-colorized-async-initialization

DepthTagger calls LanguageService always asynchronously
quotations are colorized in one simplest case
properly recognize multi-line quotations
use the lexer to colorize quotations properly
classifier supports quotations in type members
fix quotation colorization in some cases
SourceCodeClassifier finds quotations everywhere
SourceCodeClassifier recognizes quotations in constructor arguments and in sequences of expressions
SourceCodeClassifier recognizes quotations in property setters, auto properties initializers and module-level do expressions
SourceCodeClassifier recognizes quotations in tupled arguments
fix: background colors do not changed when VS theme switches
SourceCodeClassifier recognizes quotations in nested modules
adjust quotations background color to mimic the one is used for HTML by default