This thing is looking awesome. Good work!

This is a fairly decent particle editor for LÖVE.

Indeed, although Lua 5.2 will include a bitwise library AFAIK, and LuaJIT has one as well.

Right, I'm not too worried about the collision response, I just want something that works well with box2d and won't cause performance problems (line detection might have slowdowns because as far as I'm aware I would be checking against every damageable object in the game, which could be a lot).

What is a good, clean way to have laser-type (instantaneous beam which will go in a straight line to its max distance or to any object it hits, with a long lifetime) objects using the box2d API? Stuff I've tried has been very hack-ish and doesn't work quite right.

Someone (I don't recall who) made this quick thing using threads: http://dl.dropbox.com/u/4214717/threads3.love
If you have a LuaJIT-compiled version of LÖVE you can use that to see incredible speed differences, too.

An angle of 0 means right, I thought.

I'd be interested in using it. Why not use LÖVE's threads instead of coroutines?

Don't use a useful library because it has the name 'debug' in it. Got it.

Have you tried \r or \r\n? (wild guess)