[9fans] realemu update

[cinap_lenrek@gmx.de]

for everyone running realemu, please try with the new version to
see if i broke something.

the changes include:

switch back to textmode works now, as we use #P/realmodemem to
wite back changes to physical memory in the range B0000-AFFFF.

with realemu and the patch (see below), i'm able to switch to every resolution
in vmware that is suggested by the vmware vesa bios. so for everyone
who had problems with vmware graphics might give it a try.

added some i/o port emulation for pit, and some other well known ports. it
will trap now if port i/o fails.

theres a loadcom.c program that can be used to load a dos com file
into the vm and execute it (primary used for testing).  the filesystem
handles Tflush now so one can interrupt calls to /dev/realmode.

there was a bug in aux/vga causing it to produce a wrong color channel
descriptor for 32 bit rgb vesa modes, as the vesa bios doesnt report the
unused color component in the mask/pos field in modeinfo call.

see /n/sources/patch/vesa-depth32

--
cinap