First stable release

After 3 months of beta testing, Endless Sky is ready for a stable release! This release includes new types of freighters and interceptors, and updated explosion effects (shown below). Many bugs and typos have also been fixed, including a bug that made one of the Free Worlds endgame threads unwinnable, so if you are running an earlier version, please upgrade to this one.

Ubuntu packages are available in a PPA; Mac OS X and 64-bit Windows files are available for download here. Based on the Steam hardware surveys, I think very few gamers are running 32-bit Windows still, but if you desperately want a 32-bit build, file a bug report and I'll attempt to make one.