RE: [sv-bc] Mantis 1571: Add default values for macro arguments

I don't consider adding begin-end delimiters to macros to be a radical
enhancement.

It is just fixing a kludge in the original multi-line macro definition
and bringing it into line with the spirit of other language constructs.

Manta 96 and 98 have the same general spirit, for example.

Shalom

> > So we want to have a macro definition syntax which has some sort of
> > begin-end delimiters, such as `begin_define - `end_define,
> 
> If people are considering radical enhancements to the
> macro mechanism