* Add FORMAT clause to convert datetime types to string and vice versa
* Add tests for FORMAT clause
* Fixes after review
* Change TZD to TZR
* Change inline variables back to static
* Add README documentation
* Add ability to use " in raw string and ...
Use session timezone if timezone is not specified.
Add ability to use + sign in timezone offset.
Add truncating string exception.
* Move util methods from BOOST_AUTO_TEST_SUITE
* Switch back to inline variables
* Consider charset in the format string
* Add ability to write patterns without separators
* Use printf to add extra zeros
Also add extra zeros to the year patterns.
* Replace template exception with a plain function
* Clean code after review
* Fix bug with TZH:TZM when TZH is 0
* Add TZR to STRING to DATE
---------
Co-authored-by: Artyom Ivanov <artyom.ivanov@red-soft.ru>
