Update 6 - Planets and Nebulas

I've completed most of the preliminary work on the starmap editor. You can now add planets and stars, change any of their properties, and change the texture of planets.

I still need to add moons, but I imagine that won't be very difficult. After that, the only thing I have left to do before I move on to different work is adding a measurement tool to make it easier to find the distance between two objects. This will be useful for Flight Directors trying to determine travel time between two locations. I also made it so the background nebula could be changed using a seed for a random number generator. Each planetary system can have its own background, defined by the seed value. There are infinite possibilities for what the nebula could look like! I added a little randomizer button which lets you quickly switch between different seed values.