add load_module(more standard module)

1,add load_module()
2,import will use load_module
before load() will gen a none standard python module,can't been pickle.
the two above will gen a standard python module.
if thrift.file is subpath of any sys.path,use load_module is prefer.
otherwise(eg,thrift.file out of project path),use load_file.
for backward compatible,load is point to load_file

i add __name__,__file__ to load_result thrift_scheme,and add module to sys.modules while load_module()
also a gen_module_name(),try guess __name__ form thrift_file