Remove all the ugly database debug

Merge branch 'postgresql' into 'master'

Add postgresql support

Closes #3237

See merge request louiz/biboumi!18

Always free the PGresult pointer returned by PQexec

Fix a somewhat big memory leak

Handle postgresql and sqlite3 libs properly

Do not fail to compile when one of them is missing but the other one is not.

Raise an error when trying to open a database with the missing library.

see #3237

Add postgresql support