Support active patterns in signature generation

Close #685.
Use indentation from Visual Studio options
Don't regenerate contents of open buffer

Close #680.
Support union cases and record/enum fields

Fix #685.
add a InterfaceStubGenerator test
fixed: InterfaceStubGenerator smart tag does not appear in base constructor call position

remove a redundant test
Add another active patterns

Restructure TypedAstUtils for readability.
add tests for InterfaceStubGenerator.tryFindInterfaceDeclaration function
Merge pull request #691 from dungpa/go-to-metadata

Bugfixes for Go to Metadata
Merge pull request #695 from vasily-kirichenko/generage-interface-in-inherit

Generage interface in base constructor call
Handle forgotten case

When only one single case is written and it is not "pure": some inner
arguments in the pattern match case are bound to constants or there are
guards associated with the case...
Some sequence was empty while it was assumed to be non-empty
Merge pull request #702 from OkayX6/fix-union-case-gen-crash

Fix union case generation crash
Update Fantomas to 1.5.0

Fix #686.
Fix #660.
Fix #344.
fixed: FSharpEntity.TryFullName raises exception on erased types

fixed: Checker.GetToolTipTextAlternate raises exception on outdated assemblies
Merge pull request #708 from dungpa/fantomas

Update Fantomas to 1.5.0
add SyntaxConstructClassifier test for provided types
Merge pull request #709 from vasily-kirichenko/handle-fcs-exceptions-on-erased-types

fixed: FSharpEntity.TryFullName raises exception on erased types
Merge branch 'master' of https://github.com/fsprojects/VisualFSharpPowerTools into tasklistv2
Handle abbreviated union types for code generation
Handle uppercase field names