Spell Points for dnd5e

Replaces the spell slots of spellcasters with a pool of spell points. 

This implements the Variant Spell Points Rule as described in the Dungeon Master's Guide for dnd5e.

• adds a spell point tracking system to every player actor
  • displays the remaining spell points etc. in the sheet header for easy access
  • shows point costs and remaining uses in the spellbook
• automatically resets spell points on long rest and consumes them when a spell is used
• works with multi-classing
• NPC's, non-spellcasters and warlocks still use spell slots