add "apply" method variant that handles device locking itself

rename the old "apply" to "apply_to_device". meh. naming is hard.
i expect that most of the time i'd want to use the "apply" method i'm
adding here that handles device locking internally, so that is why i've
chosen to let it be called "apply" and to rename the other one.

examples/audio_playback/src/main.rs

@@ -152,7 +152,7 @@ fn main() -> Result<()> {
             }
         }
 
-        system.audio_queue.apply(&mut audio_device)?;
+        system.audio_queue.apply_to_device(&mut audio_device)?;
 
         if system.keyboard.is_key_pressed(Scancode::KpMinus) {
             volume -= 0.1;

libretrogd/src/audio/queue.rs

@@ -161,7 +161,7 @@ impl AudioQueue {
         Ok(())
     }
 
-    pub fn apply(&mut self, device: &mut AudioDevice) -> Result<(), AudioDeviceError> {
+    pub fn apply_to_device(&mut self, device: &mut AudioDevice) -> Result<(), AudioDeviceError> {
         loop {
             if let Some(command) = self.commands.pop_front() {
                 use AudioCommand::*;
@@ -196,4 +196,9 @@ impl AudioQueue {
             }
         }
     }
+
+    pub fn apply(&mut self, audio: &mut Audio) -> Result<(), AudioDeviceError> {
+        let mut device = audio.lock();
+        self.apply_to_device(&mut device)
+    }
 }