Auto equip ranged weapons before melee

Currently auto equip is favouring stun rods ahead of guns.
Improved auto equip of spare ammo clips

Only equips spares when unit doesn't already have one.
Auto equip gives pistol wielders stun rod in second hand
Improved auto equipping of stun rods

In left hand for pistol users, or in backpack otherwise.
Add isCarrying function

so we can determine if a unit is carrying a particular item.
Try not to encumber units while autoequipping

Conflicts:
	src/Battlescape/BattlescapeGenerator.cpp
Autoequip spare taller ammo in backpacks
Autoequip 2 point oh ?

Alters auto equip weapon priority

Hopefully we end up with appropriate weapons in the front ranks, support
weapons in the back ranks, and better weapons picked over deprecated
weapons.

Priorities set in ruleset.
Style fixes.
Enable loading save files from the command line

e.g. To load the save file "foo.sav" use the command
openxcom -load foo
Move autoequip weightings to RuleItem
Adds some flexibility to auto equip weightings

negative auto equip weighting means do not ever auto equip; weightings
of 1000+  means you really want this auto equipped so encumbrance and
battle type are ignored.
Some tidying up