Project compiles with xbuild

Added Mono-Debug and Mono-Release msbuild configuration for use with xbuild

Appears to build just fine! I also tried to muck around with MonoDevelop but it has some trouble with the EmbeddedResources, will try to take a look (less important). This could be a first step for getting rid of both the NAnt and the mdp/mds...

Note that the unit test project doesn't build on Windows, seems like these need to be cleaned up
    : error CS2001: Source file `xmlModel/XmlTest.ObjectLayer.cs' could not be found
    : error CS2001: Source file `xmlModel/XmlTest.Views.cs' could not be found