create pre-resultfile before tests start

[Peter Brightman]

If NUnit crashes for whatever reason, no resultfile will be written. When running many tests with different parameters, this results in creation of many resultfiles, it's hard to find out if a certain run didn't produce a resultfile, especially when there was a crash of NUnit and the resultfile is absent. If NUnit would create a pre-resultfile, with the commandline parameters within this file, and store it before the big work (the run of the tests) starts, then it would be easy to find out what testrun has to be repeated and even the parameters for the repeated run could been taken directly from the pre-resultfile. For any successful run the pre-resultfile would of course be overridden with the test resultfile as usual.