Removed redundant code

Removed code that is no longer needed. System and SystemTest have been
migrated into the Emitter classes.
Merge remote-tracking branch 'origin/master' into particle-implementation
Reverted changes

Reverted some changes caused by syncing the branches.
Block destruction particles

Added block destruction particles, as well as collision detection on the
particles.
Fixed issues

Fixed some render issues with particles and NullPointerExceptions when
destroying blocks without sprites.
Pre-merge commit

Removed test files and fixed a quick issue having to do with the
EmitterBlockDestroy blocks being removed on right click.