fix multiline task comments

In C#, VS detects a task:
/* //TODO stuff */
fix full width space treats

In C#, VS detects a task:
//　TODO stuff
fix typo
use unicodegraph
use trimChars
FindReferencesFilter does not open a document for each file until its needed
fixed: import FileSystem instead of IFileSystem, which did not work
code cleanup
Merge pull request #836 from bleis-tift/fix-task-list-comments

Fix task list comments
Merge pull request #839 from vasily-kirichenko/optimize-find-all-refs

Optimize find all refs
fixed: printf formatters are not colorized if printf function is namespace/module qualified
printf formatters are not colorized in plane strings
highlight fprintf formatters
fixed: float and wildcard printf formatters are not colorized
refactor SourceCodeClassifier
remove unused function