#57 msgbox gets lost when writing ini file back out

[Rufus V. Smith]

I don't necessarily have a good use for the message box, but when I saw it I added it. The ini write button on the misc tab doesn't preserve it, though.

[Simon Bridger]

Added MSGBOX="" placeholder to generated INIFILE, which user can edit.
Doesn't pass the actual commandline param through, as this does not have any control it is stored in.