xsetwacom: Fix off-by-one error in list_one_device

Signed-off-by: Jason Gerecke <killertofu@gmail.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Remove dead code: factor[XY]

The factor[XY] variables were introduced to make relative devices behave
more naturally by taking into account the differences between screen
space and device space. In particular, these variables were used to
provide uniform acceleration along the X and Y axes, along with
suppressing events that moved the cursor less than one pixel.

For these variables to be properly calculated, the driver needs to
be aware of the screen resolution. The necessary code has been removed
for quite some time now, making this code entirely vestigal. The server
itself should take care of everything for us as of ABI_XINPUT_VERSION
19.2, accounting for both the resolution of the device and screen
when deciding where the pointer should appear.

NOTE: Strictly speaking factor[XY] aren't /entirely/ dead. There is *one*
case where they are still set to a value other than 1.0 (setting either
TopX or TopY in xorg.conf). However, this side-effect is not at all
what is intended/expected so the functionality is still safe to remove.

Signed-off-by: Jason Gerecke <killertofu@gmail.com>
Remove dead code: struct _PROPINFO
Remove dead code: ERASER_PROX, OTHER_PROX
xsetwacom: Replace XKeycodeToKeysym with XkbKeycodeToKeysym

We're already using the Xkb functions anyway, so we may as well use
XkbKeycodeToKeysym and silence the XKeycodeToKeysym deprecation warning.

Signed-off-by: Jason Gerecke <killertofu@gmail.com>
doc: Remove deprecated Doxygen options

All options were at their default values, so safe to remove.
Update configure help to indicate that debugging is enabled by default

Running `./configure --help` indicates that debugging is disabled
by default, but this is not the case. Change the documentation to
state that it is enabled, and show the "--disable-debugging" option
to make it clear.