* Explicit mouse-related DeviceEvents
This makes the API more intuitive for common use-cases and allows us
to better propagate platform knowledge of motion semantics.
* Improve event naming consistency
* Clarify axis event forwards-compatibility
* Rename WindowEvent::MouseMoved/Entered/Left to CursorMoved/...
This emphasizes the difference between motion of the host GUI cursor,
as used for clicking on things, and raw mouse(-like) input data, as
used for first-person controls.
* Add support for windows and OSX, fix merging
* Fix warnings and errors on Linux
* Remove unnecessary breaking changes
* Add MouseWheel events to windows and OSX
* Fix bad push call.
* Fix docs, naming, and x11 events
* Remove mutability warning
* Add changelog entry
