Herwig++.cc: Redesigned steering of Herwig++, Added Herwig.h file, Cleaned main function, Created function which can be linked by external program for each run mode of Herwig++ -> Idea: run mode functions like HerwigInit, HerwigRead, HerwigBuild, HerwigIntegrate, HerwigRun will be a fixed interface / entry point which can be internally and externally invoked -> Also better in regards to unit testing -> Current commit needs a small fix for the HerwigGenericRead function which is shared by HerwigRead and HerwigBuild, will be fixed by next commit