Create "View PropertyGrid" right-click context menu action #26

See http://fssnip.net/cE for the idea. we can put the PropertyGrid in a form 
and make it popup (though we probably don't want it to be modal). Consider 
things like refreshing FsEye tree view node refreshes property grid.

The neat thing about the PropertyGrid control is that it allows to you change 
the value of some known property types.

It would be neat if we could tital the PropertyGrid window with the path taken 
from the FsEye tree view hierarchy, indicating private member access with '?'. 
e.g. x.Bla.Foo?Foo2?Foo3 

Perhaps implement this as a plugin (issue 25).