Control panel's File Manager upgrades

[Edge100x]

I've made some upgrades to the File Manager portion of the control panel. Specifically, I added a file copy option, the ability to edit files in addons/ and its subdirectories, and a button to create a new file. These should make using the File Manager a bit faster and easier.

If you have any problems accessing the File Manager or any part of the Control Panel, or something doesn't work as you'd expect, please e-mail me ASAP.