Currently simply returns output->name, but this will make it easier to
change how output names are stored in the following commits.
Also replace reading output->name with invocations of
output_primary_name. Code which writes output->name is unchanged. Done
using a mostly mechanical replacement of output->name to
output_primary_name(output).
Including config.h is necessary to get e.g. the _GNU_SOURCE define and
any other definitions that autoconf declares. Hence, config.h needs to
be included as the first header in each file.
This is done either via:
1. Including "common.h" (i3bar)
2. Including "libi3.h"
3. Including "all.h" (i3)
4. Including <config.h> directly
Also remove now-unused I3__FILE__, add copyright/license statement
where missing and switch include/all.h to #pragma once.
This commit also reworks the way focusing sticky windows is prevented by not focusing them temporarily at all, but preventing the focus in the first place.