Merge branch 'f-mixed-write-transactions' into f-move-entity

CMakeLists.txt

conanfile.py

include/caosdb/data_type.h

include/caosdb/entity.h

include/caosdb/protobuf_helper.h

include/caosdb/transaction.h

include/caosdb/value.h

include/ccaosdb.h

src/caosdb/entity.cpp

src/caosdb/transaction.cpp

src/ccaosdb.cpp

test/CMakeLists.txt

test/test_ccaosdb.cpp

test/test_data_type.cpp

test/test_entity.cpp

test/test_list_properties.cpp

test/test_protobuf.cpp

test/test_value.cpp