Add support for ! as first character of a config.sys line

[boeckmann]

FreeDOS kernel handles config.sys lines starting with an exclamation mark !.

If a config.sys line contains ! as first character, then this line can not be skipped by single-stepping.

[mateuszviste]

I may be stating the obvious, but this seems to be some FreeDOS-ism. MS-DOS does not understand "!" in CONFIG.SYS (checked on MS-DOS 6.22)

[darkstar252]

I may be stating the obvious, but this seems to be some FreeDOS-ism. MS-DOS does not understand "!" in CONFIG.SYS (checked on MS-DOS 6.22)

Obviously freedos IS not msdos only an msdos clone. Edrdos style menus are completely different from freedos msdos .