0.30 - Two new levels

This release explores the new "movable arrows/dynamite" concept further with two new levels:

• The Core: more of a novelty level than previous ones. A swarm of boulders circulates the exit, which has been blocked off with steel crates. You need to carefully thin out the boulders to blow a hole in the core. Play this one on Firefox as the input gets laggy on Chrome.
• House of Flying Arrows: this level creates Indiana Jones style pressure plates that trigger arrows by combining dynamite boulders, switches and destructors in a novel way. Fast paced with arrows chasing you around every corner.

It also fixes a rather amusing bug where you could use your flying corpse to unlock the bottom room in the Feedwater level - corpses should no longer clip through walls. Thanks to Tim for finding that bug!