Vision, aggression, attack rewrite

[brturn]

This is an experimental PR to fix #540.
Curious to get some eyes on it.

• Fixes whip/pike/flail/axe attacking invisible but revealed enemies.
• Full rewrite of the core mechanics for monster vision, aggression, and willingness to attack.
• I've verified that they can work as replacements for the original code, with minor tweaks.

Because the new functions consistently apply the 'laws' of Brogue, they also introduce some new behaviors:

• Player will attack entranced monsters when bumping.
• Confused player will lunge-attack allies.
• Confused player will spear-attack allies.
• Confused player will axe-sweep allies.
• Confused player will flail allies when passing.

Similar changes in behavior occur when replacing the original code in other areas of the codebase.