Proposed changes for version 0.2.0

I recently discovered this very useful and nice MediaWiki - congratulations!

To use in in one of my MediWiki projects, I wanted to be able to specify the MediaWiki user name instead of an email address. I implemented it and took the chance to change several other things as well.

Summary:
* MediaWiki user can be given instead of an email address.
* "alt" attribute can be changed now.
* Support of "class" attribute
* Validation of email addresses added.
* Internationalization: Currently English and German are supported.
* Minor changes to apply to MediaWiki coding standards:Now we have three .php files instead of one.
* Fixed bug: The attribute "width" was generated twice.

If you don't like all those changes feel free to take whatever subset you like.

Thanks for writing this extension!
Philipp

PS: Although I prepared almost everything to be the "0.2.0" release I did not update the .phar part and the build.xml because I'm not familiar with .phar.