Add invulnerable damage flag, godmode and damage flag commands (#1949)

* Add invulnerable damage flag and commands

* Add serialization for damage flags

* Add godmode command

Resources/Groups/groups.yml

@@ -102,6 +102,9 @@
   - readyall
   - factions
   - signallink
+  - adddamageflag
+  - removedamageflag
+  - godmode
   CanViewVar: true
   CanAdminPlace: true
   CanAdminMenu: true
@@ -197,6 +200,9 @@
   - readyall
   - factions
   - signallink
+  - adddamageflag
+  - removedamageflag
+  - godmode
   CanViewVar: true
   CanAdminPlace: true
   CanScript: true