add AsyncMaybe CE
use AsyncMaybe in ImplementInterfaceSmartTagger
InterfaceStubGenerator make argument names' first char lower case
cosmetics
fix argument indexing in InterfaceStubGenerator
fix after rebase
fixed: InterfaceStubGenerator duplicates property setter arguments
add a InterfaceStubGenerator test for property setters
Merge pull request #376 from vasily-kirichenko/implement-interface-argument-names

Implement interface argument names
add tests for InterfaceStubGenerator.normalizeArgName
Merge pull request #378 from vasily-kirichenko/add-interface-stub-generator-tests

Add tests for InterfaceStubGenerator.normalizeArgName