Feature/draganddrop

Hiya, Here's the pull request for the drag and drop functionality for IR Group editor windows. I had to rewrite the GIT history to make it get the changes correctly

The list of stuff for any logs you keep is:
* Drag and Drop of Servos in Editor and Group Editor
* Drag and Drop on empty group
* Pane scrolls when you drag to top or bottom of window
* Set a variable for window width and tweaked it
* Set a variable for button height and tweaked it
* Changed the Arrows to arrows

I'd guess you dont need the project file changes, but I'll leave the merge to you