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 combines `output_by_name` and `output_by_identifier` into a single
function called `output_by_name_or_id`. This allows for output
identifiers to be used in all commands, simplifies the logic of the
callers, and is more efficient since worst case is a single pass through
the output list.
This commit enhances the output transform
command with options for a relative transform,
i.e. the provided transform will be applied as
an offset to the current transform. Append
`clockwise` to rotate clockwise from the current
rotation, or `anticlockwise` to rotate in the
opposite direction.
For example, if the output LVDS-1 is rotated
90 degrees clockwise, the command
`output LVDS-1 transform 90 clockwise`
will rotate the display to 180 degrees.
All transform options are supported,
including flipped transforms.
Relative transforms can only be applied to
a single output and cannot be used with
a wildcard (*) output specifier.
