Feature Added, the Remove <Item> Context Menu

I added in the ability to remove modules, drones, implants and boosters using the context menu.

In order to do so I had to modify the ContextMenu class to include a reference to the view that was spawning the menu. In the process I added a new remove method in the fittingView, droneView, implantView and boosterView classes and moved all common item removal code to it's respective method.

I have not had time to bug test the code thoroughly. I did test to verify that all three methods of removing items work, IE. delete key, double click, context menu. I also verified that selecting and removing multiple modules from the fitting using the context menu works.