- use unsigned ints only (where mixing signed/unsigned)
- turn heap_swap into an inline function, add SWAP_TVAL macro to swap values using a temp value as storage.
- added type checking SHIFT3/4 macros
also style cleanup for CTR_Map
- update face normals when triangulating.
- avoid divide by zero when interpolating customdata on a zero length edge.
- replace zero float comparisons with fabsf() < FLT_EPSILON to avoid numeric error.
also renamed BLI_heap_empty() --> BLI_heap_is_empty() so its obviously readonly function.
