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.
Also contains two other small changes:
- Clicking any button will focus the container clicked (not just left)
- Remove seamless_mouse (doesn't make sense on wlroots)
