Gamma & Epsilon alerts levels (#8517)

* Add Gamma & Epsilon alert levels

* Add license for epsilon sound

* Remove mention about gamma armory

* Add missing license sources

* Delete unused sound

Resources/Audio/Misc/license.txt

@@ -0,0 +1,3 @@
+epsilon.ogg made by dj-34 (https://github.com/dj-34) taken from https://github.com/ss220-space/Paradise/blob/05043bcfb35c2e7bcf1efbdbfbf976e1a2504bc2/sound/effects/epsilon.ogg
+
+siren.ogg taken from https://github.com/ParadiseSS13/Paradise/blob/master/sound/effects/new_siren.ogg

Resources/Locale/en-US/alert-levels/alert-levels.ftl

@@ -15,5 +15,11 @@ alert-level-violet-announcement = There is a viral threat on the station. Medica
 alert-level-yellow = Yellow
 alert-level-yellow-announcement = There is a structural or atmospheric threat within the station. Engineering staff are advised to immediately respond and perform safety measures. Crewmembers are advised to stay away from the threat, and stay in their workplaces if necessary.
 
+alert-level-gamma = Gamma
+alert-level-gamma-announcement = Central Command has ordered the Gamma security level on the station. Security is to have weapons equipped at all times, and all civilians are to immediately seek their nearest head for transportation to a secure location.
+
 alert-level-delta = Delta
 alert-level-delta-announcement = The station is currently under threat of imminent destruction. Crewmembers are advised to listen to heads of staff for more information.
+
+alert-level-epsilon = Epsilon
+alert-level-epsilon-announcement = Central Command has ordered the Epsilon security level on the station. Consider all contracts terminated.

Resources/Prototypes/AlertLevels/alert_levels.yml

@@ -21,9 +21,21 @@
       announcement: alert-level-yellow-announcement
       sound: /Audio/Misc/notice1.ogg
       color: Yellow
+    gamma:
+      announcement: alert-level-gamma-announcement
+      selectable: false
+      sound: /Audio/Misc/siren.ogg
+      disableSelection: true
+      color: PaleVioletRed
     delta:
       announcement: alert-level-delta-announcement
       selectable: false
       sound: /Audio/Misc/delta.ogg
       disableSelection: true
       color: DarkRed
+    epsilon:
+      announcement: alert-level-epsilon-announcement
+      selectable: false
+      sound: /Audio/Misc/epsilon.ogg
+      disableSelection: true
+      color: DarkViolet