Build 23

Build 23 is now live and includes the following:

Major visual overhaul!

• all levels now have proper floor tile details
• main and transition levels have some extra background details
• improve boss particles, align lighting colour with animation state
• add some background animation (spinning fan blades)
• spinning objects now have a little "anchor" point rather than just fading to nothing

Other changes

• fix for some particles escaping (or getting stuck in) level geometry (blood, boss impact, steam)
• minor changes to main level generation, plus some special surprises in the transition level progression (you'll see...)
• simple lefty support (A/D for movement, however, W/S not implemented for looking up/down yet)