better aiming, better explosions, better music

Decent little update, mostly finesse. 

• Full 360 degree aiming now possible. you can attack, thrust, and throw in all 360 degrees.
  • aiming logic has also been reworked, it should be easier to aim now
• better switching of music
  • tracks now switch on the nearest measure or the nearest nth measure after a chunk destruction
• better explosions
  • destroying an enemy chunk now nets a longer more elaborate explosion. more rewarding for when you just destroy something via slash. looks okay for now, will revisit it again later.
• enemy chunk damage tweak
  • previously, an enemy chunk would be split open with about 1/3 health remaining. This has been changed to 1/2 health remaining - this offers a better value proposition for using the thrust/throw attack. Before, you could easily and reliably destroy the chunk with two more consecutive slash volleys if your slash speed was high enough, kinda undermining the thrust/throw attack's utility. 
  • enemy chunk healths have not been increased - so maybe the game is slightly easier now.