This adds a few settings to control global render quality, for faster
renders when tweaking lighting etc. The implementation is not so great,
and this should really be part of a proper render profile and preset
system. So for now it's a hidden Peach feature, enabled by setting rt
to 1. Before the next release, I'll either remove or improve it.
Settings are:
- Maximum subsurf level
- Child particles percentage
- Maximum shadow map samples
- AO and SSS quality factor