Include actual line content in parse error message

When configuration file parsing fails in an early phase, the actual offending
line will now be logged in the error message to make it easier to pinpoint
the problem.

Original Description
Currently a configuration setting that is not in any [section] generates:

Failed to read configuration file '/etc/maxscale.cnf': Section starting at line 2 has no name or name is empty.

It would be nice to also have the actual line content printed for easier debugging (and also to avoid "do we count lines from one or zero" confusion)