whoops, fixed wrong time keeping :-(
implemented SemanticHandler/Checker + Checker
reduced unittest verbosity
introduced Identifier in Semantic Model
removed deprecated islistof
fixed typo and handler not descending on Extension
fixed bad reraising
introduced UnkownType
added more checks for UnknownType
added class name to @warn output
initial work on Inferrer (systematic solutions)
illustrating optional typing information
added more assertion messages
taking unhanded exception handling offline