0024257: Minor corrections for building / testing on VC++ 11

0024257: Minor corrections for building / testing on VC++ 11

Several corrections coming from building and testing on MSVC++ 11:
- compiler warnings corrected in structiges.c (32-bit mode) and BOPAlgo (64-bit mode)
- DRAW command for testing exceptions (OCC6143) refactored for getting some output even if process fails (problem with stack overflow handling)
- DRAW command readstep removed as it leads to hang-up in Debug mode due to waiting for user input; the only test that used it changed to use testreadstep command