A few other bugfixes and some more doubtful 8-bit character patches.

The first two are plain simple bugfixes.  The third needs thought.

I should have mentioned that none of my 8-bit patches make isalpha()
& co treat any latin-1 8bit characters as letters, they just make sure
these functions do not return garbage.  (To make them letters, one
would call setlocale(LC_CTYPE,"").  However, that would break code
like 'foo = (isalpha(c) ? tolower(c)-'a' : -1).)

== 90-palette.dif ==
Bug:  main-acn.c compared 'char' with 'byte'.  Would fail when 8th bit was set.

== 92-strnicmp.dif ==
Bug: my_strnicmp was buggy.  Replace it with a prefix() call.

== 98-uchar-changefmt.dif ==
Possible bugfix: More 8-bit char patches.  Need inspection.