return result from partial_function and behavior
added convenience function cow_tuple::drop_left
ostream support for cow_tuples in variant visitor
fixed bug in pattern matchin w/ leading wildcard
ostream support for match_hint
ostream support for cow_tuples in variant visitor
added tl_right meta function
fix pedantic compiler warnings

this patch fixed a warning regarding the return type of lambda
expressions consisting of more than just a return statement
improved pattern matching unit test
experimental typed_actor impl + test