Merge contiguous coplanar mesh facets into single n-gons.

Input parameters:

1. Ms → Mesh whose facets to merge.
2. Tl → Absolute planar tolerance.
3. Ah → Allow the creation of n-gons with holes.
   •  True → Allow
   • False → Disallow

Output parameters:

1. Ms → Mesh with merged coplanar facets.
2. Cn → Number of newly created n-gons.