[Oberon] LOOP conversion

[Andreas Pirklbauer]

    > This is exactly a reason why LOOP/EXIT shouldn't be
    > allowed by the compiler not even for "porting” reasons
    > Jörg

Agreed. So it now seems that an even better approach to port V4
may be to *first* clean up V4 *on* a running V4 system (i.e. replace
all LOOP, EXIT, RETURN, etc) in a step by step fashion *while*
keeping the V4 system running, and *then only* compile V4 for
RISC5, either using a cross-compiler on V4 or on RISC5 itself.