The current particle system uses dynamic allocation of particle
instances for keeping track of particle instances. This adds unnecessary
overhead in case the code does not need a handle to this particle which
is the case in pretty much all instances.
The new non-persistent particles are stored in a standard vector without
dynamic allocation which should make the processing steps using this
vector much faster and allow better scalability in case more particles
are used by a mission.
Previously, the source orientation was always aligned to the world so it
couldn't adapt to a weapon that changes direction. This fixes that by
introducing a "relative" mode for source orientations that is enabled by
default and disabled if the direction is set explicitly.
asarium