Version 1.10

Changes:

• added method sounds:play_random
• added "random" play button to tests
• changed to require "prepend" to prefix sound files with "sounds_"
• fixed inheriting "prepend" attribute when concatenating SoundGroup instances with arithmetic operator
• added iSoundGroup object meant for use with sounds prefixed with "sounds_" only
• fixed length of clock_tick so loops
• deleted "node_place_metal" sounds duplicates of "node_dug_metal"
• deleted some of the less useful compound groups
• renamed sounds:
  • some "ar_fire sounds" to "ar_burst"
• added sounds:
  • ar_burst
  • cicada
  • explosion
  • explosion_distant
  • explosion_scifi
  • fireworks
  • fireworks_pop
  • fuse_short
  • ghost
  • ghost_damage
  • ghost_death
  • helicopter
  • melee_hit
  • plasma_shot
  • scrape
  • shears
  • zombie_damage
  • zombie_growl