Per-application desktop mode settings are no longer supported.  Apps
can be launched in a specific desktop window by using:

  explorer /desktop=name[,widthxheight] app.exe [args]

If the named desktop already exists the app is launched inside it. The
default desktop is cleverly named "default".

If window station and desktop aren't inherited from the parent, don't
connect to them from the server, but from the USER init code where we
can get the proper values from the startup info structure.

the per-winstation table.

doesn't exist.

- Set ContextFlags accordingly in save_vm86_context().
- Raise debug exceptions correctly for debug exceptions.
- Do not clear TF bit for VM86-generated debug exceptions.

Some apps, for no particular reason, call fflush() on files opened for
read.  This keeps them from tripping over their shoelaces.

- fixed lexical rules for a path name
- fixed identifier rules so that we get the right precedence
  between ! and ::
- modules (in mod!name forms) are now handled as tIDENTIFIER
  (tPATH was buggy anyhow)