Desired features exposed in C bindings

[tvandinther]

There are a few features that would be nice to expose in the C bindings for client development. The list can grow but as of now these are the features I want to implement in a client library.

• Database::open_remote
• Connection::changes
• Connection::last_insert_row_id
• Connection::query
  • Specifically with params (both positional and named) (currently stubbed)

There are several others but these should be enough to get a mostly useful client library running.