Allow triggering audio playback on clients.

[oznogon]

Most non-UI sounds in EE play back only on the server, not on clients.

SP/EE were designed for in-person LAN play where the server typically functioned as the main screen and was within earshot of all players on a ship. With online play, the server is often viewed only by the GM, if at all.

• SP should provide a method of triggering sound playback on clients as well as the server.
• SP should provide a method of triggering sound playback on specific clients via scripting.

See also #241 about asset synchronization with clients, which would be required for custom audio assets stored only on the server to be triggered or played back on clients.