Add supports const char * value for type parsing.

both rac_setArgument:atIndex: and rac_argumentAtIndex: .
Revert previous change
Skip const type qualifier
Fix ushort type code parsing for -rac_returnValue
Skip const type qualifier for -rac_returnValue
Merge pull request #484 from kkazuo/typeparsing-const-pointer

Add supports const char * value for type parsing.
Merge pull request #485 from kkazuo/typeparsing-ushort

Fix ushort type code parsing for -rac_returnValue