Blender Git Loki

Alembic: Fix crash of viewport render with strands read from alembic cache

The issue was caused by RNA passing ownership from the cache data used by Blender
to Cycles. This lead to situations when all of a sudden blender looses data it
was expecting to have.

Now instead of passing ownership we're just copying strands from the data, so both
Blender and Cycles are having it's own local data.

Ideally this data will be shared between viewport and Cycles, but that's a bit
more tricky to do without modifying RNA API. Would happen eventually tho.