Merge pull request #56 from vasily-kirichenko/master

fix: FSharpVSPowerTools.Logic and FSharpXmlDoc projects don't build without VS 2012 installed
Reuse Refactor menu and set focus to active document after refactoring

Internal rename menu item is still hidden.
Add docs and an option to disable rename reafactoring
support double backtick ident rename. #59
Cache ProjectProviders forever
Merge pull request #60 from bleis-tift/support-double-backtick-ident-rename

support double backtick ident rename. #59
fix: ProjectProvider cache can fail if there's no containing project
Merge pull request #61 from vasily-kirichenko/project-loading-optimization

Projects loading optimization