First pass at cleaning up tests/ dir before moving the rest

First pass at cleaning up tests/ dir before moving the rest

Original commit message from CVS:
* configure.ac:
* tests/bench-complexity.scm:
* tests/bench-mass_elements.scm:
* tests/complexity.c:
* tests/complexity.gnuplot:
* tests/instantiate/.cvsignore:
* tests/instantiate/Makefile.am:
* tests/instantiate/caps.c:
* tests/mass_elements.c:
* tests/network-clock-utils.scm:
* tests/network-clock.scm:
* tests/plot-data:
First pass at cleaning up tests/ dir before moving the rest
Combined with CVS surgery