This allows marking a MenuItem as a default action, e.g. in a
context menu for an action that reflects what e.g. a double click
would perform.
Also enhance the window menu to mark the close action as the
default, and when double clicked perform that action.
Fixes#1289
Each window now has an associated progress integer that can be updated
via the SetWindowProgress IPC call.
This can be used by clients to indicate the progress of ongoing tasks.
Any number in the range 0 through 100 indicate a progress percentage.
Any other number means "no progress"
It didn't feel right to have a "DHCPClient" in a "Servers" directory.
Rename this to Services to better reflect the type of programs we'll
be putting in there.
