[Fluxus] particle opacity

[Dave Griffiths]

> i could not set the opacity of textured particles. i realized the alpha
> component is not set when drawing particles in line 106 of
> libfluxus/src/ParticlePrimitive.cpp. changing glColor3fv to glColor4fv
> seems to fix this. is this ok? or is there a reason for this behaviour?

Fine I think - I guess in the past I've always done alpha in the texture.
There are probably similar calls to glColor3f around the place that could
be changed.

cheers,

dave