removing autogen dependency

[Nikos Mavrogiannopoulos]

Hi,
 I was thinking options to allow supporting virtual servers under a
single server with different configuration / authentication methods,
and it seems that the simplicity of autogen's configuration parsing is
prohibiting anything like that to come in a natural way (e.g., via
sections [0]). Given the overall issues I've seen with autogen, I
believe that irrespective the previous limitation, dropping that
dependency would make maintenance easier. Although autogen is good
software, it introduces quite some complexity and none of its unique
features were used, or were necessary in ocserv.

I've experimented with the inih library, which provides basic
ini-style parsing, and the outcome seems promising. The code is
simpler and more easily extendable. On the other hand, eliminating
that dependency results to a quite large patch [1].

Given that, it would be nice to have a second pair of eyes on that
patch (or even testing, other than the CI). Anyone willing to try
reviewing that branch or testing?

regards,
Nikos

[0]. https://gitlab.com/ocserv/ocserv/milestones/6
[1]. https://gitlab.com/ocserv/ocserv/issues/134