[m-rev.] for post-commit review: convert ssdebug to use var_tables

[Zoltan Somogyi]

For review by anyone.

The more intricate part of this diff is the update of polymorphism_type_info.m.
The posted diff works, but I expect to make more changes shortly. I posted
the diff in its current state because reviewing each part separately should be
a lot easier than reviewing a single change that does several things at once
to the same block of code.

The diff is with -b.

Zoltan.
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