Rewriting the language scripts, to introduce the concept of optional messages: messag...

Rewriting the language scripts, to introduce the concept of optional messages: messages which can be translated, and can be ommited, without problems. Including linkprefix and imgmultigotopost in the optional messages list (more will be included in the future), and adding the EXIF messages to this list if requested, instead of filtering them out from all the messages; also, fixes of typos, minor bugs and code style.