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
add resolve unopened namespaces docs skeleton
try to fix the issue with ModuleSuffix attribute
extract AssemblyContentProvider from LanguageService
AssemblyContentProvider works properly with entities included into modules with CompilationRepresentationAttribute (CompilationRepresentationFlags.ModuleSuffix) attribute
fixed: UnopenedNamespacesResolver does not work with anonymous modules properly
add icon to "open namespace" smart tag action
fixed: Unopened namespaces resolver inserts open statement above namespace if there are no other open declarations
refactor according to the review
AssemblyContentProvider: remove generic type argument count from all ident parts

AssemblyContentProvider: does not return modules themselves
replace imperative loops involving arrays mutation with Array.map/mapi
ResolveUnopenedNamespaceTagger resets current word and state as it stats calculating new smart tag
add Resolve unopened namespaces screencast
Merge pull request #537 from vasily-kirichenko/fix-module-suffix

Fix module suffix
fixed: Unopened namespaces resolver does not show the smart tag on type name in type extensions
extract InsertContext.adjustInsertPoint function
extract rest of Resolve unopened namespaces logic to Core project

make tests more end-to-end
fix general settings page layout

update settings dialog screenshots
decrease version from 1.3.0 to 1.2.6