Blender Git Loki

Fix T59339: Particle render without baking issues
Fix T61289: Emitting particles from instances not working properly

The first issue has been re-introduced by a code which was dealing
with missing hair after opening the file. That was re-setting all
particle systems all the time because modifier flags were not copied
back to original. This made every modifier run to be seem as an
initial file open.

Now we copy flags back to an original modifier. But also we are
trying to not do any resets unless needed in that case. This way
we can preserve in-memory caches.

Other part of the change is related on re-setting particle system
if number of mesh elements changed. But we only do it if the
modifier has been already evaluated once.