fix bug where liquids don't stabalize in radial gravity

nx and ny are declared at the start of update_particles_i, but not reinitialized before the liquid attempts to move, so it will always try to move up and left first, and probably succeed.
PROT goes through portals
fix invisible PHOT bug when going through GLAS sometimes
Comments for some of the liquid movement code
still allow NBLE to ionize at high temperatures (probably won't interfere with fusion)
fix nx/ny again (values were reversed)
make sure no effect FILT mode doesn't affect BRAY
backport lua code highlighting from my console
Merge branch 'develop' of git://github.com/simtr/The-Powder-Toy into develop

Conflicts:
	src/simulation/elements/SPRK.cpp