Merge branch 'f-extended-c' into f-remove-unique-result

README_SETUP.md

doc/capi/index.rst.in

include/caosdb/entity.h

include/caosdb/status_code.h

include/ccaosdb.h

src/caosdb/entity.cpp

src/caosdb/transaction.cpp

src/ccaosdb.cpp

test/test_ccaosdb.cpp

test/test_entity.cpp