Rename raw input to raw mouse motion, cleanup

This renames 'raw input' to 'raw mouse motion' as there are other kinds
of raw input.  The update path is restructured to avoid reinitializing
all of disabled cursor mode.  Modification of shared state is moved out
into shared code.  Raw mouse motion is disabled by default for
compatibility.

Related to #1401.

README.md

@@ -158,6 +158,8 @@ information on what to include when reporting a bug.
   per-joystick user pointers
 - Added `glfwGetX11SelectionString` and `glfwSetX11SelectionString`
   functions for accessing X11 primary selection (#894,#1056)
+- Added `glfwRawMouseMotionSupported` function for querying raw motion support
+  (#125,#1400,#1401)
 - Added headless [OSMesa](http://mesa3d.org/osmesa.html) backend (#850)
 - Added definition of `GLAPIENTRY` to public header
 - Added `GLFW_TRANSPARENT_FRAMEBUFFER` window hint and attribute for controlling
@@ -171,6 +173,8 @@ information on what to include when reporting a bug.
   (#676,#1115)
 - Added `GLFW_JOYSTICK_HAT_BUTTONS` init hint (#889)
 - Added `GLFW_LOCK_KEY_MODS` input mode and `GLFW_MOD_*_LOCK` mod bits (#946)
+- Added `GLFW_RAW_MOUSE_MOTION` input mode for selecting raw motion input
+  (#125,#1400,#1401)
 - Added macOS specific `GLFW_COCOA_RETINA_FRAMEBUFFER` window hint
 - Added macOS specific `GLFW_COCOA_FRAME_NAME` window hint (#195)
 - Added macOS specific `GLFW_COCOA_GRAPHICS_SWITCHING` window hint (#377,#935)
@@ -182,7 +186,6 @@ information on what to include when reporting a bug.
 - Added `GLFW_OSMESA_CONTEXT_API` for creating OpenGL contexts with
   [OSMesa](https://www.mesa3d.org/osmesa.html) (#281)
 - Added `GenerateMappings.cmake` script for updating gamepad mappings
-- Added `GLFW_RAW_INPUT` input mode and `glfwRawInputSupported` function (#1401)
 - Made `glfwCreateWindowSurface` emit an error when the window has a context
   (#1194,#1205)
 - Deprecated window parameter of clipboard string functions
@@ -203,7 +206,6 @@ information on what to include when reporting a bug.
 - Bugfix: The gamma ramp generated by `glfwSetGamma` did not use the monitor
           ramp size (#1387,#1388)
 - [Win32] Added system error strings to relevant GLFW error descriptions (#733)
-- [Win32] Moved to `WM_INPUT` for disabled cursor mode motion input (#125)
 - [Win32] Removed XInput circular deadzone from joystick axis data (#1045)
 - [Win32] Bugfix: Undecorated windows could not be iconified by the user (#861)
 - [Win32] Bugfix: Deadzone logic could underflow with some controllers (#910)
@@ -233,7 +235,6 @@ information on what to include when reporting a bug.
 - [Win32] Bugfix: A title bar would be drawn over undecorated windows in some
                   circumstances (#1383)
 - [Win32] Bugfix: Standard cursors were not per-monitor DPI aware (#1431)
-- [X11] Moved to XI2 `XI_RawMotion` for disable cursor mode motion input (#125)
 - [X11] Replaced `_GLFW_HAS_XF86VM` compile-time option with dynamic loading
 - [X11] Bugfix: `glfwGetVideoMode` would segfault on Cygwin/X
 - [X11] Bugfix: Dynamic X11 library loading did not use full sonames (#941)
@@ -437,6 +438,7 @@ skills.
  - Cyril Pichard
  - Keith Pitt
  - Stanislav Podgorskiy
+ - Nathan Poirier
  - Alexandre Pretyman
  - przemekmirek
  - Philip Rideout
@@ -490,7 +492,6 @@ skills.
  - Santi Zupancic
  - Jonas Ådahl
  - Lasse Öörni
- - Nathan Poirier
  - All the unmentioned and anonymous contributors in the GLFW community, for bug
    reports, patches, feedback, testing and encouragement