Initial implementation of printf highlighting

Only those print functions that have the formatting string in the first position are enabled. Missing are: bprintf, fprintf, fprintfn, kbprintf, kfprintf, kprintf, ksprintf
Merge branch 'master' into printf

Conflicts:
	src/FSharpVSPowerTools.Core/SourceCodeClassifier.fs
	src/FSharpVSPowerTools.Logic/SyntaxConstructClassifier.fs
	src/FSharpVSPowerTools/SyntaxConstructClassifierProvider.cs
	tests/FSharpVSPowerTools.Core.Tests/SourceCodeClassifierTests.fs
Merge branch 'master' into printf

Conflicts:
	src/FSharpVSPowerTools/SyntaxConstructClassifierProvider.cs
Publish a bugfix release in v1.4.5
refactor Entity.tryCreate tests
UnopenedNamespacesResolver shows the smarttag on first part of long idents only
Handle nested modules in signature generation

Close #678.
Update VS 14 solution
Merge pull request #681 from vasily-kirichenko/resolve-unopened-ns-firts-ident-only

Resolve unopened ns firts ident only
Merge pull request #684 from dungpa/nested-modules

Handle nested modules in signature generation
Update to FCS 0.0.61
Remove the workaround on extension properties
Merge pull request #688 from dungpa/fcs

Update FCS to 0.0.61
Read test projects from external project files
Support multiple projects in VS unit tests
Add missing functionalities to ProjectParser
Make sure test projects are built before testing

Fix #640.
Skip the failing test on CI
Merge pull request #687 from dungpa/vs-tests

Support multiple projects in VS unit tests
Don't gray out override members

Close #622.

FCS never returns more than one symbol for override members. We skip
these in checking unused symbols for now.