Fix various typos

Mainly fix typos in comments, but also some minor code changes:

* Rename `apply_on_poiner` to `apply_on_pointer`.
* Rename `ImeState::Commited` to `ImeState::Committed`
* Correct `cfg_attr` usage: `wayland_platfrom` -> `wayland_platform`.

src/platform_impl/linux/x11/event_processor.rs

@@ -1692,7 +1692,7 @@ impl EventProcessor {
 
     /// Send modifiers for the active window.
     ///
-    /// The event won't be send when the `modifiers` match the previosly `sent` modifiers value.
+    /// The event won't be sent when the `modifiers` match the previously `sent` modifiers value.
     fn send_modifiers<T: 'static, F: FnMut(&RootELW, Event<T>)>(
         &self,
         modifiers: ModifiersState,