bugfix: support string constants
bugfixes: inline functions; function array args to pointers; Callback.get_rtypes()

* don't try to attach to inlined functions
* when a function argument is an array, use a :pointer as the arg
* callback get_rtypes() wasn't getting the "_t" at the end of uint64_t, Type was returning a string, not a symbol
enhancement: C enums now become FFI enums