Compute local AO in per-pixel room

[Frankie]

We need the ability to compute AO in the per-pixel room while taking the painted depth per texel into account (local occlusion). Right now the AO only takes the geometry into account (only captures low frequencies) and it requires to export the mesh+depth map to external programs if we want to capture local occlusion (hi-frequencies) which breaks the worflow.

Also the current AO implementation uses a light array which is not precise enough and leaves ugly shadows. It should use ray casting with parameters to set number of rays and max ray distance.

There has been some requests about this in the past so I'm pretty confident I'm not the only one needing this.

Franck.