clutter/evdev: Take over stylus configuration

Stylus configuration (stylus buttons, pressure) was handled
at the very high level, doing the button and pressure translations
right before sending these to wayland clients.

However, it makes more sense to store these settings into the
ClutterInputDeviceTool itself, and have clutter apply the config
at the lower level so 1) the settings actually apply desktop-wide,
not just in clients and 2) X11 and wayland may share similar
configuration paths. The settings are now just applied whenever
the tool enters proximity, in reaction to
ClutterDeviceManager::tool-changed.

This commit moves all handling of these two settings to
the clutter level, and removes the wayland-specific paths

https://bugzilla.gnome.org/show_bug.cgi?id=773779

clutter/clutter/evdev/clutter-input-device-tool-evdev.h

@@ -59,6 +59,8 @@ struct _ClutterInputDeviceToolEvdev
 {
   ClutterInputDeviceTool parent_instance;
   struct libinput_tablet_tool *tool;
+  GHashTable *button_map;
+  gdouble pressure_curve[4];
 };
 
 struct _ClutterInputDeviceToolEvdevClass
@@ -72,6 +74,11 @@ ClutterInputDeviceTool * clutter_input_device_tool_evdev_new      (struct libinp
                                                                    guint64                      serial,
                                                                    ClutterInputDeviceToolType   type);
 
+gdouble                  clutter_input_device_tool_evdev_translate_pressure (ClutterInputDeviceTool *tool,
+                                                                             gdouble                 pressure);
+guint                    clutter_input_device_tool_evdev_get_button_code    (ClutterInputDeviceTool *tool,
+                                                                             guint                   button);
+
 G_END_DECLS
 
 #endif /* __CLUTTER_INPUT_DEVICE_EVDEV_TOOL_H__ */