Request #30059: Implement interface to Win32 resource dialogs.

All dialogs under the menu Usage->GeneralPreferences, with the
exception of the Editor Preferences are now stored as resources, but
should still work as exactly as before.  The difference this change
makes is to allow more flexibility in the layout of controls on the
dialogs created as resources.  All dialogs will eventually be stored
as resources, but this is a separate task.

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Request #30318: Add createDialog to WindowsGui structure

The following functions have been added to the WindowsGui structure:

    val findResource : hinst * string * res_type -> word
    val lockResource : word -> unit
    val loadResource : hinst * word -> word

    val getModuleHandle : string -> hinst
    val loadLibrary : string -> hinst
    val freeLibrary : hinst -> bool

including the addition of the res_type and hinst.

Test that users can get a handle to resource dialogs from any 
executable or library by calling LoadLibrary to get the handle to 
the library followed by a call to WindowsGui.createDialog (new for 
this request) specifying the library handle, parent window of the
dialog, and the resource name of the dialog.