v0.6.0

• Breaking: Raw pointer handles now use NonNull where appropriate, to avoid null pointer dereferences.
• Breaking: Renamed empty methods to new, and take parameters in most of those, to better match normal Rust semantics.
• Breaking: HasRaw(Display/Window)Handle::raw_(display/window)_handle returns a result indicating if fetching the window handle failed (#122).
• Breaking: Remove the Active/ActiveHandle types from the public API (#126).
• Breaking: Remove AppKitWindowHandle::ns_window and UiKitWindowHandle::ui_window since they can be retrieved from the view (#129).
• Breaking: Remove Copy derive from RawWindowHandle and WindowHandle (#140).
• Implement PartialEq, Eq and Hash for WindowHandle too. (#128)
• Implement the relevant traits for &mut T where T: <trait>. (#130)
• Add web handles for wasm-bindgen v0.2. They are locked behind the wasm-bindgen-0-2 feature. (#134)
• Deprecate the raw window/display handle traits. They will be removed at the next stable release. (#139)