KDevelop Project and Filesystem view improvements

Since I'm from Austria I had to attend the KDevelop/Kate sprint which is held in Vienna this year. Thanks to Joseph for organizing the sprint. We are having a great time here - hacking all day long...

After two days I have been productive and implemented a few small but still possibly useful features.

Since quite some time the project view supports moving items using drag and drop.  However copy was not supported. I added there a drop menu allowing you to copy - and as a side effect also allow you to cancel an accidental move operation.

The second new feature is similar: it gives you the possibility to copy/paste items in the project view through the clipboard. Even pasting files that where copied eg. in dolphin is supported.

The third one is bookmark support for the filesystem view - just a kate has it. The bookmarks are stored per session. This can be useful for web developers to store the fish:// locations of test/production servers for quick access.

And last but not least, it is now possible to add two filesystem views - which might be useful to connect to test/production server.

All features can be found in master branch and will not be in the recently released KDevelop 4.4. But 4.5 will follow early next year...