Fixing is_utf8() to allow valid ASCI non-printable characters.
avoid editing managed string, fix fersion
The string buffer pointed to by message_class_name appears to be managed by the php engine, since duplicate strings (e.g. literal class names) are being stored in the same place. Assuming it is much safer to increment the pointer variable itself rather than mess up with the buffer's contents.
Might fix chobie/protoc-gen-php#7