This patch contains the starting point for an implementation of a software DOS emulator for ReactOS. It already supports loading COM files and a few DOS API calls. This program currently requires the use of the softx86 library (which can be found here: http://sourceforge.net/projects/softx86/ and should be added to the "3rdparty" library directory), but since this library is not maintained and not fully implemented, i wrote wrappers around it in the ntvdm code so it can be easily replaced by a different x86 emulation library. I have also considered the possibility of writing a new x86 emulator library. Furthermore, softx86 has certain bugs which prevent ntvdm from working, so i will upload a patch that fixes them soon.