sneaky AI -- currently psychic about visible tiles

Conflicts:
	src/Battlescape/Pathfinding.cpp
take cover better! grr!
trying to make the aliens less dumb
AI work in progress

Conflicts:
	src/Battlescape/UnitWalkBState.cpp
	src/Engine/Options.cpp
	src/OpenXcom.2010.vcxproj
new cover AI seems to be functional!

sectoids are scurrying well

Conflicts:
	src/Savegame/BattleUnit.cpp
parentheses!
trying to put the I in AI, not quite there yet

tile-scoring based on LOS to soldiers works now, apparently
BattleUnit badly needs a copy constructor
added flags to BattleUnit to try to add some continuity to AI actions
probably more?

Conflicts:
	src/Savegame/BattleUnit.cpp
cover AI seems better than ever

some clean-up in AggroBAIState
mean soldier distance calculated in survey function
XXX dynamic_cast to AggroBAIState in handleAI() does not work, investigate
copy constructor written for BattleUnit for proper operation of survey...()
total TU cost of calculated path is available from Pathfinding now

Conflicts:
	src/Savegame/BattleUnit.cpp
attempts to make AggroBAIState persist

so far, meh
Reapers charge and attack now!

bam
don't be dumb, reapers
reapers can't always attck while facing target

changed the valid melee range check to not consider direction when a 2x2 unit
is actually in range to attack, just as it ignores direction when looking for a
position to run to for an attack
put _DEBUG back in Makefile.am, more AI fixes

actually consider distance from action target to aggrotarget, at least a little
bit, duh
still can't get reapers to attack more than x4
clean-up and comments

things seem to be running fairly well
spaces -> tabs
fix for crippling AI bug, change to pathfinder

aliens know about all soldiers known to any alien when pathfinding; they use
their space-walkie-talkies
Fixed: Items removed from store when researched.
Fixed: map<>::find() return values were not checked.
clean-up, fixed action 3 cover lock-up