This adds an improved single battle mode to OpenXcom trunk (improving the "new battle" button in the menu UI). It tries to make getting an acceptable battle quickly, reducing the amount of fiddling needed to set options.
Changes include:
*Random selection of research completed: not all items are usable in all battles, e.g. can get battles where Plasma weapons are not usable if taken from dead aliens
*Random selection of alien equipment level: aliens are not always equipped to level 0, but instead 0-2 (so can get battles versus heavy plasma wielding aliens)
*No longer field only rookies: randomly promote + increase stats of some soldiers
*No longer provide 100 of each item
*Randomly setup the battle in UI (mission type, alien race, difficulty, darkness, craft, terrain) while still permitting choice if desired
*Currently, in addition to the "New Battle" button in the UI, adds a "New Random Battle" button
This patch works for me (tm) and could be cleaned up for commit if desired.