[Mono-winforms-list] Managed.Windows.Forms now built by default

[Peter Dennis Bartok]

Hi All,

Just figured I'd let everyone know that if you build mcs from source, MWF is 
now being built by default, instead of the (now completely) obsolete 
Wine-based version.

To allow the switch, we had to add a few empty and partially stubbed out 
classes that were DataGrid related. I also checked in placeholders for the 
dialogs several contributors have been working on to support this move, 
those will be replaced with the real deal as soon as they are finished.

This should resolve some of the confusion and problems people trying to use 
MWF ran into.

Also, if you are keeping build instructions, make sure you update them 
accordingly (Paul! :-) )

Cheers,
  Peter