next iteration: make the support dependent on TEST parameters

next iteration: make the support dependent on TEST parameters
-DTEST_CACHING: try the cache
-DTEST_CACHING_VERBOSE: make it say what it does
-DTEST_CACHING_RECHECK: don't trust the cache and compare the extracted
    value with the actual package contents (thus making it slower once again)

Quite a few more checks along the way, in general