Fix most of the FIXMEs in project2

I fixed all of the FIXMEs except for one.

The missing one is the "auto next move" mode. I think it's not drawing the intermediate steps because of the way that Gnome2/Gtk2 work. The canvas is only updated after the event callback returns - that is, after the button click is fully done. I did some tests with the Gnome2 example app to confirm this. Without a deeper understanding of Gtk programming I can't fix that one - presumably there's a way to make the canvas and all items redraw from within an event handler?

Also, as a side effect of fixing the Target not being drawn issue, I removed most of the code related to moving the Target, and replaced it with a copy of the code used to move the UAV. I realise you were trying to have an elegant and generic move subroutine, but it was simply easier for me to replace it with the working UAV move routine, sorry. You can always retrieve and fix the old version from Git history, if you want.

Finally, just want to say it was kinda interesting to do - it'd been a while since I looked at Gtk.