1.8 Beta 3

I've updated the NEXT branch to 1.8 Beta 3. This version fixes various bugs and adds a few minor changes:

• Sung slave camps have been improved to increase the chance that slave quarters survive.

• Acid-filled containers no longer damage cargo items; instead, they damage armor.

• Mining cargo hold keeps track of asteroids not yet mined.

• New images for fuel depots and armor dealers.

The complete list of fixes is here: https://ministry.kronosaur.com/program.hexm?id=1&status=closed&tag=102