Added sound settings page

+ added sound setting page
+ added sound setting icon
+ moved sound settings from interface settings

Added master volume

+ added master volume slider.
+ volume can be changed by sliding bar or by using the spin box
+ Preview of  volume will be played when dragging and releasing bar.

Added checks for qt4

Qt4 does not have support for setting the volume without some lengthy
work around, I have disabled volume control for qt4 users and have
mentioned that "Master volume requires qt5".

Updated sfx

+ removed all old sfx
+ added new end step and tap sound
+ tap/endstep sound has a timer on it to prevent spamming
+ test sound engine will now use endstep sound

Made end step sfx softer

end step felt too harsh

Added player joined sound

+ added a sound for when a new player joins a room

Updated

Was missing a sound when a player joins

Made end step softer

Made end step even softer

updated sound again

cockatrice/src/settingscache.cpp

@@ -79,6 +79,14 @@ SettingsCache::SettingsCache()
     showMentionPopups = settings->value("chat/showmentionpopups", true).toBool();
 
     leftJustified = settings->value("interface/leftjustified", false).toBool();
+
+    masterVolume = settings->value("sound/mastervolume", 100).toInt();
+}
+
+void SettingsCache::setMasterVolume(int _masterVolume) {
+    masterVolume = _masterVolume;
+    settings->setValue("sound/mastervolume", masterVolume);
+    emit masterVolumeChanged(masterVolume);
 }
 
 void SettingsCache::setLeftJustified(const int _leftJustified) {