Re-implement correctly the handling of failure to open the database

If we can’t open it at startup, we exit.
If we can’t open it on reload, we keep the previously-opened database.

This way, we’re assured to always have a valid and open database available.

Merge branch 'orm' into 'master'

Pure c++ sqlite3 ORM

Closes #3271

See merge request !11

Explicitely close the Database before re-opening it

Implement our own database ORM, and update the whole code to use it

Entirely replace LiteSQL

fix #3271

In reload.cpp, only build the database things if litesql is used

Move reload.*pp from louloulibs to src

Properly catch and handle database errors

Do not use a singleton for the database.

fix #3203

Clean the Config module, use static things instead of a stupid singleton

louloulibs is directly included, instead of being a submodule

Because this is a nightmare to manage