Dur..duh...dur..duh!

Finding an event to base July's splash (haha) screen around was slim
pickins however I eventually opted for Shark week/month! In terms of
updates to BeeBS I've finally got all menus and screens to have VT52/100,
Mode 7 and ANSI support so no matter what you're connecting with you have
the option of ASCII/ANSI/Teletext art.

I would love to take the credit for this amazing ASCII shark however it
goes to snd (accessed from ascii.co.uk).

Improvements have been made to message navigation, you now have the
ability to backtrack through message threads with the - key. This was not
too difficult to implement as if a message is a reply the subject of is
changed to 'Reply to msg' so using a combination of
IF,INSTR,LEFT$,MID$,RIGHT$,STR$ and VAL it's possible to detect if the
message is part of a thread and if it is allow the user to backtrack to
the previous message number and then display said message.

The message header formatting has had a slight upgrade in Mode 7 (although
currently remains the same in ANSI).

Finally I got a little fed-up of entering the time each time I started
OBBS, I've cobbled together a work around so that OBBS will instead use
the Master 128's RTC.

I'm confident that there is a much more efficient way to do this however
within the confines of the existing OBBS code this was the best I could
think of. If you have any ideas on how to reduce the length of FNnmonth
please let me know so I can save some precious bytes!