New BaseSphere parent, GasGiant derivaed and GasGiant shader, materials files.
Adding new files to Pioneer and Graphics projects.
Integrate and use new BaseSphere, GasGiant and materials.
Update the Linux auto-make files.
Bring some more functionality into the BaseSphere class, mostly static methods to take the implementation details out of Pi.cpp
Then delay generating the GasGiant textures until they're either visible or a reasonable period of tie has elapsed.
Change the default delay before generating the gas giant textures to 60 seconds instead of 5. 5 is ok on my hilariously-fast PC, not so much on others!
Remove a static member, it's two methods, it's increment and a couple of unused variables.
Create a small placeholder texture for the planet so there is something to see right from the start.
Merge pull request #2803 from fluffyfreak/gas-giant-planB

Merging Gas Giant rewrite.
Gas Giant rewrite (#2803)
Fix signed/unsigned comparisons again.
Properly initialize members of Sector, Sector::System, StarSystem, SystemBody.
auto-commit: translation updates
auto-commit: translation updates
auto-commit: translation updates