rfc: mscoree: Use the mono embedding api instead of invoking mono.exe.

[Vincent Povirk]

This is a patch that has mscoree.dll load mono.dll in-process rather
than starting mono.exe. This is needed so that (among other things),
the running process gets the correct values from GetCommandLine and
GetModuleFileName(0).

The code quality is probably not very good, so I'm sending it to
wine-devel for feedback first.