improv(Startup Sequence): Implement priority system in case multiple arguments...

improv(Startup Sequence): Implement priority system in case multiple arguments have been used (see CommandlineParser). When the GUI is used, display a splashscreen whilst SPC is loading (see ServerPackCreatorSplash). CLI menu for an improved user-experience, giving the user more choice when running in commandline (see ServerPackCreator). The Main-class now only initializes ServerPackCreator and runs it with the determined mode.