Skills and API update

- ISkillItem: Lets an item allow use of skills
- ISword: Item counts as a sword for purposes of skills
- IDashItem: Item can be used with Dash skill
- Updated Dash skill, improved movement vector length
- Updated SwordBeam, adding canExecute method
- Updated Rising Cut's canExecute to also check canUse
- Updated Mortal Draw to allow all sword items
- Possible fix for disappearing swords using Mortal Draw
- Armor Break, Dash, Ending Blow, Parry, Spin Attack, and Sword Break
can be used with both swords and ISkillItems
- Fixed possibility of parrying a blow after switching to an
inappropriate item for both Parry and Sword Break
- Shields now implement IDashItem
- Modified and added methods to PlayerUtils for checking player's held
item skill compatibility
- Helper method in PlayerInfo cleans up canExecute checks
- Responsibility for checking held item shifted to canExecute / canUse
methods of skills, rather than during key input
- Dodging an attack successfully now has a sound notification
- Added hurt flesh sounds; used during combo for non-swords
- Combo miss sound plays for all misses, not just swords