Patch tested by compiling with `__attribute__ ((format (printf, 2, 3)))`
applied to `cmd_results_new`.
String usage constants have been converted from pointers to arrays when
encountered. General handler format strings were sometimes modified to
include the old input string, especially for unknown command errors.
This adds support for `i3 4.16`'s ability to set the title alignment.
The command is `title_align left|center|right`.
When the title is on the right, marks are moved to the left. Otherwise,
they are on the right.
