Todo list for next development free-time:

 - For 16-bit MS-DOS apps: dpmie16.asm should provide a function that
   allows other code to call protected mode routines. The reason for
   that is in large model EXEs (multiple code segments) we cannot
   assume the code segment given matches up with other code segment
   pointers. If we truly want to enable DPMI entry & exit we have to
   have a "proxy" call routine which allocates descriptors if needed,
   sets their bases to whatever realmode segments it was called with,
   and then jumps into protected mode and calls the realmode proc
   from protected mode using those segments. This is the final step
   before you will be able to implement the SSE tests for 16-bit
   MS-DOS apps from within the Windows DPMI DOS box.

 - SSE testing code for 16-bit MS-DOS from within Windows 3.0, 3.1,
   95, 98, ME, XP, etc.

 - For 16-bit Windows apps: If the DOS version number implies that
   were running under OS/2, then do not carry out the SSE test.

