Driving out of a map in tactical with a vehicle causes an unhandled exception, crashing the game (exe 7667 using bigmaps and ice-cream truck).

Happens in multiple sectors and seems to be 100% reproducible.

• r7818: Fix: enemy artillery shells were wrongly attributed to have been fired from the first merc you hired, leading to lots of complaints about friendly fire.
• r7819: Fix: crash when entering a sector if currently selected merc is in the helicopter
• r7822: Fix: during strategic AI evaluation, player strength should be taken into account. However, due to very bad programming/deletion of code (not sure which one, probably both) not only is player strength not calculated sometimes, the variable isn't even initialized. Which can lead, to say, the AI assuming that the player has 54k mercs defending a sector, at which points it decides 'Nope, not going there'.
  We now at least initialize the thing to 0, so the AI can properly attack.
• r7823: Technically not a fix, but it sure feels like one: As you might know, the AI cyclically evaluates the strategic situation and sends out garrison/patrol replacements. It creates a list of all sectors viable to be reinforced, then picks one of them (somewhat) randomly. However, if it then decides that it cannot send forces there (because, say, the sector has over 54k defenders), it does not send forces - it stops for this cycle.
  I've changed this so that in this case, it simply tries to send forces to the next sector on the list, until it is successful. This seems to be in line with what the AI should originally do. The combination of these 2 bugs (r7822 && r7823) could lead to the strategic AI being severely dumbed down, sending out teams at a much lower rate then was originally intended.