Pyvcg

* Fix bug in printing smtlib string literals. They are now correctly
escaped for both quotations and non-printable characters.

* Fix bug when printing smtlib comments with newlines.

* Fix bug where an uninterpreted function declaration did not
contribute correctly to the logic selection.

* Adjust required Python version to 3.8 to 3.10 (as that is what CVC5
currently supports).

* First release