Revert "Use if constexpr to make things a lot more readable"

This reverts commit d62ca9f87906be6f046fe9d07afb8bfb69c166e3.

Use if constexpr to make things a lot more readable

Fix the INSERT query for types that don’t have any Id column

This should fix the int conversion warning on 32bits arch

Restore the is_one_of variable template

Merge tag '7.2'

Merge branch '3332-version-7-x-should-work-with-gcc-4-9-as-stated-in-install-file' into 'v7'

Compile with gcc 4.9

See merge request louiz/biboumi!22

Remove a variable template usage

Because it’s only supported in gcc>=5.0

Merge branch 'postgresql' into 'master'

Add postgresql support

Closes #3237

See merge request louiz/biboumi!18

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

Remove many log_debug from the database module

Use a more precise return type, instead of auto

Add a 0 default value for template argument N

Merge branch 'orm' into 'master'

Pure c++ sqlite3 ORM

Closes #3271

See merge request !11

Fix compilation (many warnings, and a linkage error) with clang++

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

Entirely replace LiteSQL

fix #3271