Employ a slightly different API for ParticleEmitter value randomization on @Hanmac’s suggestion.
Include -Wall for better code quality
Fix warnings in mrb_timer.cpp
Fix warnings in mrb_audio.cpp
Fix warnings in mrb_level_player.cpp.
Fix warnings in mrb_moving_sprite.cpp
Use new Range API also for return values
Add more methods to ParticleEmitter for MRuby