New asteroids

So I've plundered NASA's archives and then played merry hell with their images and created a bunch of new asteroid images - this is ones that can be used as assets (which I intend to do for an upcoming expansion of the trader faction; new systems that won't impact on what someone else seems to be doing with them but it will almost certainly link in fine with them). There are also a few extra D class planetoids and the updating of the license...

I should also apologise for the odd strange thing in my pull requests and other stuff as I apparently still have a little to learn about how git works... I merged the pulled branches and removed them but apparently I shouldn't have bothered merging them?