[Oberon] Batch processing of Oberon commands

[Andreas Pirklbauer]

Extended Oberon now contains a simple batch processing facility,
which allows users to activate multiple commands as follows:

Oberon.Batch
   ORP.Compile A.Mod B.Mod C.Mod ~
   System.Watch ~
   MyModule.MyCommand A B C ~
   ~

which executes the set of commands until the return code
of any command is different from zero or the syntax is not
that of a valid Oberon command.

Any command can, but does not have to, set a return code by
calling the procedure Oberon.Return(res), for example:

   Oberon.Return(3)

within the command. This essentially sets a global variable

  Oberon.Par.res

which can be checked after a command has been executed.
Oberon.Par.Res is reset to zero before command activation.