URL upload plugin

[Tesla2k]

Hello,
Since in Version 1.5 the URL upload feature is missing. I wrote a little plugin to get it back.
It works a little different than the original, because it was easier to code this way.

It's the first time I ever coded something for coppermine. The code is ugly and lacking some usual standards. E.g. everything is hardcoded in german.
So if you wish the contribute you are very welcome.

[Αndré]

Thank you for your contribution. I just did a quick test and it worked as expected (at least if the source file is hosted on my localhost, but that's an issue with my testbed).