Testrunner.tcl enhancements: (1) Attempt to build the SQLite tcl extension

if it is not already available.  (2) testrunner target "devtest" is added as
an alias for "mdevtest".  (3) Try to keep summary information at the end of
a test below 80-characters per line.  (4) Update the Makefile.in so that
the "clean" target removes the tcl extension built by item 1 above.

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