New pause sound effects (#81)

New pause sound effects, all of them of my own authorship and under CC-BY 4.0.

Author: M374LX

samples/pause_appear.wav

@@ -163,6 +163,10 @@ font;fonts/tiny.png;CC0;Robey Pointer;opengameart.org;
 font;fonts/Roboto-Medium.ttf;Apache-2.0;Christian Robertson;;
 font;fonts/Roboto-Bold.ttf;Apache-2.0;Christian Robertson;;
 font;fonts/Roboto-Black.ttf;Apache-2.0;Christian Robertson;;
+sound;samples/pause_appear.wav;CC-BY 4.0;Alexandre Almeida (M374LX);m374lx.users.sourceforge.net;
+sound;samples/pause_cancel.wav;CC-BY 4.0;Alexandre Almeida (M374LX);m374lx.users.sourceforge.net;
+sound;samples/pause_confirm.wav;CC-BY 4.0;Alexandre Almeida (M374LX);m374lx.users.sourceforge.net;
+sound;samples/pause_highlight.wav;CC-BY 4.0;Alexandre Almeida (M374LX);m374lx.users.sourceforge.net;
 sound;samples/break.wav;CC-BY 3.0;Mateus Reis (KZR);;
 sound;samples/checkpoint.wav;CC-BY 3.0;Mateus Reis (KZR);;
 sound;samples/jump.wav;CC-BY 3.0;Mateus Reis (KZR);;