Slight modifications to our make.bat and maketests.bat files to make them generate NMake Makefiles (as opposed to JOM ones). Indeed, ideally, we would generate JOM Makefiles, but even though Qt Creator uses JOM to effectively build OpenCOR, it still generates NMake Makefiles (after all, NMake and JOM Makefiles are the same). So, now we can build OpenCOR from the command line and then switch to Qt Creator without first having to make clean everything.