Improve the documentation

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
doc: move relative motion normalization page over to doc/

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
doc: drop touchpad button behavior page - provided in doc/ now

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
doc: move "device configuration via udev" page to here

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
doc: improve seat documentation

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
doc: document the calibration as well

Requires MathJax for client-side, but that's an easy dependency to accept and
better than requiring Latex to build the documentation.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>