Lots of balances updates + improved bosses + minor fixes

Problems this update aims to fix:

- Some bosses are too weak.
- Melee weapons are weak compared to ranged weapons.
- Wrong damage type for many weapons.
- Touching damage from enemies was too FPS dependent, and less affected by armor (due to min damage of 1). Also you could dash through enemies unharmed sometimes.
- Fixed some missions that were too hard / too easy.
- Fixed auto-balance to be less brutal.
- Fixed issue that sometimes bosses would spawn on the player because you don't know where they'll appear.
- General balances.


Actual changes:

- Changed the way touching damage works - will now deliver more damage but less often.
- Redraw grass sprites.
- Fixed occasional error with music dispose when volume is 0.
- Removed 'melee' type from 'Sunder'.
- Added 'magic' type to 'Aura of Purity'.
- Changed 'Axe' main type to 'melee'.
- Removed 'range' type from 'Banish'.
- Removed 'range' type from 'Blessed Hammer'.
- Added 'trap' type to 'Breakpoint'.
- Added 'trap' type to 'Exception'.
- Added 'melee' type to 'Daggers'.
- Removed 'range' type from 'Fire Bomb'.
- Removed 'range' type from 'Poison Bomb'.
- Added 'melee' type to 'Staff'.
- Fixed 'Scorched Earth' type to 'fire'.
- Added 'melee' type to 'Shield Bash'.
- Added 'Melee' powerup.
- Made Max Armor a per-hero property, so that some heroes may have more armor than others.
- Changed the 'Iron Skin' skill to increase max armor at top 3 levels.
- Changed bosses to always spawn at the same place but mark it.
- Added some pause after bosses spawn so they won't attack immediately.
- Added death explosion to bosses.
- Added unique sounds to Dragon boss.
- Slightly decreased auto-balance extra spawns.
- Made the 'Obelisk' level easier.
- Made the 'Hold Gate' levels easier.
- Made the 'Ranger' slightly weaker.
- Made the Priest's 'Divine Protection' stronger.
- Made the Skeleton Mages slightly weaker.
- Made auto-balance spawn slightly less extra enemies.
- Made the auto-balance slightly less harsh.
- Removed the mouse position reset when menu shows.
- Fixed mouse to be visible when moved even when window is not focused.
- Made 'Enihpares' faster and stronger + added axe attack. Also reduced his touching damage.
- Added swinging animation to 'Blood Tree'.
- Added flying ability to the 'Serpent'. Also reduced his touching damage.
- Fixed 'Ballistra' typo.