#41 Fix up registers on tape load trap

[Darren Salt]

This patch causes the tape load trap code to set
various Z80 registers more or less in accordance with
the behaviour exhibited by a real Spectrum, or at least
FUSE when told to not use tape traps.

Some simplifications have been made to account for the
fact that some load errors simply don't happen (e.g.
there are no incomplete bytes in TAP files or in TZX
standard-speed blocks).

Some testing is still needed :-)

The DE=0 patch (1.113->1.114) must be reverted before
application of this patch.

[Darren Salt]

[Philip Kendall]

Logged In: YES
user_id=29214

Applied; I haven't tested it any further than checking that
it works for a few 'normal' programs as well as The Rats.