Blender Git Loki

fix [#24780] Metaballs are not drawn correctly in new scenes

this is a can of worms, at the moment blender depends on broken behavior for metaballs:
find_basis_mball() can return a metaball object that fails a is_basis_mball() check which makes this logic very confusing (added note about this in mball.c).

Metaballs needs a refactor however at least make drawing fail consistently,
For wire draw is_basis_mball() wasn't being checked, for solid drawing it was (hence the strange wire frame).

For now the motherball needs to exist in the main scene else it wont work.