* Document the connector API method is_transaction_active()
* Move mysql::connection_base::is_transaction_active() to the other transaction-handling methods.
* Add more tests for mysql::connection::is_transaction_active()
* Add postgresql::connection_base::is_transaction_active()
* Add tests for postgresql::connection_base::is_transaction_active()
* Change the type of the SQLite3 transaction status from transaction_status_type to a boolean flag.
* Add sqlite3::connection_base::is_transaction_active()
* Add tests for sqlite3::connection_base::is_transaction_active()
* When closing a transaction do it in the following order: report (if any), execute SQL command, set transaction active flag to false.
Leak: The sqlite3 connection handle destructor was
accidentally turned into a default constructor during the
migration of repositories.
Replaced the sqlite3 raw pointer with a unique_ptr to prevent
this kind of accident.
Changed sqlite3 usage tests to be linked into one executable.
This provokes multiple definition errors for non-inlined free
functions.
Also ran clang-format on the changed headers.
