Add a Makefile for OpenWatcom using WMAKE. This is a horrible version
of Make, but since it's bundled with OpenWatcom it is probably better
to stick to it. It has the nice property that it can produce DOS,
Win32 or OS/2 binaries.
This Makefile currently assumes that it is hosted on a system where
pathname separators are backslashes. For cross-compiling using
OpenWatcom on a Linux system it is probably better to write a separate
Makefile using GNU make to invoke Watcom.
a) Automatically generate dependencies for all Makefiles;
b) Move register definitions to a separate .dat file;
c) Add support for "unimplemented but there in theory" registers.
