Adds keybindings for screen rotation and auto rotation from an accelerometer.

Find an accelerometer device in sysfs (cat /sys/bus/iio/devices/iio*/name, or using a script: monitor-iio.sh)
Find the raw output file of the accelerometer (e.g. cat /sys/bus/iio/devices/iio:device0/in_accel_x_raw should output an integer).
Add the raw output file names to the dwl configuration accel_*.

Add a udev rule to uniquely identify the device, for example:

sudo echo 'SUBSYSTEM=="iio", KERNEL=="iio*", ATTR{name}=="accel_3d", GROUP="input", SYMLINK+="input/accel"' >> /etc/udev/rules.d/99-accel.rules
sudo udevadm control --reload-rules && sudo udevadm trigger

(the device is probably already in /dev/ e.g. /dev/iio:device0 but on my computer the number changes after a reboot)

A symlink to the device should now be available in /dev/input/ and accessible to input group members.
Add the device path to the dwl configuration accel_path.

• rotation_enabled: If the auto rotation is enabled on startup.
• rotation_delay: How often to check the accelerometer values in milliseconds.
• rotation_flat: Threshold on the normalized Z axis to consider the device flat and stop the auto rotation.
• rotation_thresh: Rotation threshold after which the screen flips (values less than 0.5 will cause a back and forth).

• accel_path: The path to the accelerometer device file (e.g. "/dev/input/accel").
• accel_x: The name of the sysfs file for the accelerometer x axis.
• accel_y: The name of the sysfs file for the accelerometer y axis.
• accel_z: The name of the sysfs file for the accelerometer z axis.

Default keybindings:

• <Modkey> + <Shift> + <Arrows>: Change the screen rotation manually (doesn't disable the auto rotation).
• <Modkey> + <Shift> + <R>: Enable/disable the auto rotation.

• 2022-10-25

• Unprex