Merge pull request #114 from Bertram25/development

Worked on fixing #6
Merge pull request #115 from Bertram25/development

Completed the CREDITS file with latest info
Worked on improving the GUI.

- I added the graphics needed for scrolling and the in-game windows frame.
- I made the corresponding changes in cegui files to display the new scroll bars.
I'll work on the windows frame cegui changes in another commit.

Part of #5