Add missing feature from original config where filename starting with a '+' actually represent a host name, to be mounted and browsed.

[frachel]

Missing feature from the "combined" config program -

The original Atari config had a feature where if a filename started with a + sign, such as +xyx.com it would take everything to the right of the + sign, mount it as a new host, and go to it's directory listing (see here: https://github.com/FujiNetWIFI/fujinet-config-old/blob/master/src/diskulator_select.c#L364)