go lang: fixed passing normal and keyword args when making a new instance of a class.
go backend: allow passing functions and methods to other functions as callbacks.
note: this requires the return type enclosed in '(' and ')', example a callback that takes int and returns int: `def f( callback:func(int)(int) ):`
go backend: simple array slices `a[n:n]`
fixed evaluation order `a = False and (False or True)`
go backend: `range` builtin.
fixed exception expressions (PEP463)
fixing regtests
fixed annon functions in dicts or keyword args in normal mode