Battle scripting

[rversteegen]

The (not yet detailed) write-up for this plan is on the wiki.

There are a lot of parts to implementing battlescripting, including:

• script multi-tasking
• run the script interpreter during battles, and trigger scripts with attacks, formations, or spawned enemies
• new commands for triggering attacks, messages, victory, etc
• new commands to inspect or modify battlers (enemies and hero), distinct from enemy data and out-of-battle hero states
• new commands for inspecting or modifying queued & occurring attacks
• enemy AI scripts
• use scripts to define attack damage, attack hit/miss/fail, valid targets, chaining