WIP [ready for review] use gaudi_add_compile_test for test_public_headers_build
cf issue #19
- this removes the option GAUDI_TEST_PUBLIC_HEADERS_BUILD
- this removes a few build targets (one per subdir with dependencies on each public header in that subdir. these targets were not built by default. there are still the executables that are built by the tests, that remain non-default build targets, actually one object file and the binary.)
- this adds tests matching the regex '.test_public_headers_build.'
PS: please squash when merging.