Added a tutorial on UPDATEs, transactions and multi-queries
Added a tutorial on connection_pool
Added a tutorial on error handling
Added examples on INSERTs and DELETEs
Rewrote the discussion page on character sets
Added a discussion page on the templated connection class
Removed superseded examples on timeouts and multi-queries
Updated the coverage build to gcc-14 (gcc-13 was using a non-LTS release
that caused problems)
Contributes to #365 and #366
