Patch 41 complete: Bug fixes + some performance improvements.

# 3.1.
I have disabled the exploration mode save file deletion for now.
Fixed a bug causing autoaim modules to not count as revolute joints.
Fixed a bug in the validity check of joints.
Added a big text warning when your ship is invalid while in the editor.
You can no longer leave the editor with an invalid ship...
Added OpenGL profiling functionality. If you get performance issues, you can go to the settings menu, hit F8 and activate it. The profiling output is written to the log.txt files along the rest.
Improved the rendering performance of the background grid.