Added Ending Blow; further overhauled skills

- Added Ending Blow skill
- Combo overhaul: tracks consecutive hits and last entity hit
- Combo overlay uses text shadows, better color values
- Rising Cut now uses performComboAttack method
- Moved canExecute(EntityPlayer) to SkillActive for easier use
- Added getActiveSkill method to PlayerInfo for easier casting
- Improved activation, especially Mortal Draw and Dash
- Optimized mouse event, especially right click
- Fixed keybindings not respecting all conditions for key presses: stun,
attack time, etc.
- Added grunt sound when fail to lift a block
- Config option to require full health for Sword Beam
- Sword Beam now disables actions for a short time (it was far too
spammable)