Find all surface faces whose planarities fall within a given deviation.

Input parameters:

1. Sf → Surface for face search.
2. P- → Lower limit of planarity deviation.
3. P+ → Upper limit of planarity deviation.

Output parameters:

1. Fc → Found face surfaces. When the lower limit exceeds the upper limit, planarities that fall between the limits are omitted instead.
2. Ix → Found face indices. When the upper limit is smaller than the lower limit, planarities that fall between the limits are omitted instead.