$LastChangedDate: 2008-11-26 23:42:38 -0500 (Wed, 26 Nov 2008) $

Module for special-effects.

The major object is the FX container.
It is the interface for creating (and the container of) special-effects
such as explosions and smoke trails.

Particle-system and FX container:
The particle-system classes should be treated as private implementation of the FX container.
The FX container provides high-level methods to create them and automatically expires them.

Classes of particle-systems:
The two primary classes are SmallParticleSystem and BigParticleSystem.
Small particles render quickly (as OpenGL point-sprites) but have deficiencies.
Big particles are full-featured (update callbacks, can be rotated, etc)
but too many of them will slow rendering.
