0025945: Make stable checking of shape global properties in tests

- Added function checkprops, set default tolerance parameter to 1.0e-4
- Using "area" instead of "square".
- Options "-equal\notequal" isn't used together with "-s" in blend and offset test cases.
- Correct regressions/differences/improvements and CPU problem (set props tolerance to 0.1)
- Corrected test cases to use checkprops proc.
- Correct image difference
- Updated TODOs in test cases.
- Updated test cases to get correct images of result shape

tests/boolean/bopcommon_simple/S5

@@ -5,4 +5,4 @@ box b2 -r -r 0 1+r 1+r 2
 bop b1 b2
 bopcommon result
 
-set square 17.0816
+checkprops result -s 17.0816