Should be the last bit of sculpt/paint code, now this is fully using BLI_task. Note that PBVH normals update is now about 20% quicker than with OMP code (from 27ms to 21ms with a big stroke over a 500k vertices monkey), even though a missing thread-protection was added... atomic primitives ftw! For the records, with the missing `#pragma omp critical` section added, previous code was like four times slower (above 100ms).