[ffigen] Support for Prefix and Names in config. (#20) - Support for global prefix and prefix replacement in functions/structs/enums - Handles all internal name collisions (such as those between - dylib identifier, ffi import prefix, any typedefs generated, array helper classes, expanded array items, declarations, init function) if a collision occurs its suffixed by `_cr<int>` - Added tests for prefixing and collisions