Occuances of joined_tables have become a bit scarce after changes
since 1.0.

This fixes syntax errors due to DEFAULT being generated inside a case
expression.

In contrast to the AST dumper, there is no use for XSTL postprocessing
at the moment, and it's more compact/convenient to analyze in the
logging db.

sqlite: Use them.

Needs to be a separate class for the impedance matching to work.

Makes it look less intimidating in doxygen-generated html.

Fix resulting warnings.