fix all warnings
fixed: DepthColorizer hides standard Current Line highlighting
fix code formatting issue
add IProjectProvider and DummyProjectProvider (for standalone fsx files)
rename DummyProjectProvider -> VirtualProjectProvider
fixed: Rename refactoring dialog does not appear if renaming symbol is not declared in the current project
reformat code according to our style
Merge pull request #87 from vasily-kirichenko/master

fixed: DepthColorizer hides standard Current Line highlighting
Merge pull request #89 from vasily-kirichenko/rename-dialog-fixes

Rename refactoring dialog does not appear if renaming symbol is not declared in the current project
Move most of constant strings to Resource module

Also display error icons in message boxes.
Merge branch 'vasily-kirichenko/standalone-files'
- separating VS2013 specific functionality into separate assembly
- keep removing statics used to share dependencies

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merge with upstream
save active documents as pairs filepath -> snapshot instead of IWpfTextViews