Experiment with refactoring the internal sql interface a bit. My
original goal was to modify the schema and thus refactor to a state
where it would be sane to write tests for dc_sqlite_open() (and/or
however it ends up refactored) to assert schame changes before/after.
The function does a cast and does not create a new objects. The
stdlib convention is to use to_*() for functions which return new
objects and as_*() for functions which keep referring to the same data
but using a different type. Follow that convention.
* Start replacing int with bool where possible (#18)
* Continue replacing int with bool where possible (#18)
* Continue replacing int with bool where possible (#18)
* Run fmt
