Add float support to ConfigurationNode.
Add a few more spell result types.
Hopefully fix weird arrows produced by ProjectileSpell.

Also remove hard-coded sound effects in preparation for new effect
system.
Add support for Color to ConfigurationNode.
Remove the leatherskin and ironskin spells. They feel pointless.
Implement config-driven effects.

WHEW!
Add configurable wand particle count.
Fix effect trails.
Fix reloading spells on the fly.
Documentation update.
Tweak some effect defaults.
Fix blink targeting.
Prepare for 2.9.3 release.
Fix the arrow spell(s).
Fix effects on fill selection.
Make the demo wand modifiable to avoid confusion. It will also use mana now.