BBctrl should not auto-open alphabetically first nc file on startup

[MagnmCI]

Steps to reproduce:

1. Open NC file, make sure it's what you want
2. Home and zero machine
3. For some reason, you turn the machine off
4. Turn machine on again
5. Re-home and re-zero machine
6. See that a program is open - surely it's the one you opened before - and hit run
7. You are now running the alphabetically first nc file in files rather than the last opened file and you crash the tool

Obviously, the correct answer here is to check the nc file again before hitting run - but I would also argue that opening the alpha first file by default is not the right behavior.

Instead it should open nothing and you must explicitly open an NC file on each power-on -OR- there is some do-nothing 00Defaults.nc file that's always there which always alpha sorts first and thus opens, to block running the wrong program by mistake -OR- open the last-opened file so if the machine (and control) have to be power cycled, you don't get caught out by having the wrong program open.

Thanks for listening.