the buildsystem will now pick up and link
all test cases according to the layer, e.g.
backend tests will automatically be linked
against the backend + library solely.
test.h introduces a PLANNED_TEST() macro for C code, shows what tests
are provided and so on (the nobug version did that since some time).
test names are now passed as identifers and translated to strings by the
macros.
A lot fixes for existing tests, replace some printfs with ECHO, cosmetics.
one threadpool (sync_many) test is broken and set to PLANNED, this needs
further testsuite support for dispatching output.
add a TEST nobug flag to test.h
