Collapse mesh facets whose properties exceed given threshold values.

Input parameters:

1. Ms → Mesh whose facets to collapse.
2. Ar → Optional area limit. Facets with areas smaller than this limit will be collapsed.
3. As → Optional aspect ratio limit. Facets with aspect ratios less than this limit will be collapsed.
4. El → Optional edge length limit. Facets with edges whose lengths are smaller than this limit will be collapsed.

Output parameters:

1. Ms → Mesh with collapsed facets
2. Cc → Number of collapsed facets