Don't show warning when no step soundfx are defined
Fix item count display in action bar

For non-equipped items, we display the item count when it is >= 0. For
equipped items and regular powers, the item count is hidden.
Merge pull request #1280 from dorkster/fixes

Hide step sfx warning and fix actionbar item count display
When spawning enemies, don't block tile before checking requires_status
Fix spawn powers not working when their initial target was blocked
Use cooldowns from power definitions for enemy power cooldowns

This obsoletes the related cooldown keys in enemy definitions.
Obey power cooldowns for map events that trigger powers
Replace passive_attacker with combat_style in StatBlock

Instead of being a boolean, combat_style has three possible values:
- default: the existing behavior for creatures
- passive: only enters combat when attacked (i.e. passive_attacker=true)
- aggressive: is always in combat
Merge pull request #1284 from dorkster/fixes

Obey power cooldowns; introduce "combat_style"; collision bugfixes
Use syntax from "enemy" map layer for spawn powers/events

Fixes #1282

This change gives some benefits:
- no crashes, since we've already established a list of valid enemy file
names
- "fuzzy" enemy type selection. For example, we can spawn any type of
antlion by using "spawn_type=antlion"

So to spawn a normal antlion, we used to have:
    spawn_type=enemies/antlion.txt
Now we'll use:
    spawn_type=antlion_normal
Merge pull request #1285 from dorkster/fixes

Use syntax from "enemy" map layer for spawn powers/events