Add support for Elytra as chest pieces in class chests.

Makes the class chest armor guessing logic pair `"ELYTRA"` up with the
chest piece slot. This specific matching works, because there are no
underscores in the `"ELYTRA"` item name.

Fixes #616

changelog.md

@@ -13,6 +13,7 @@ These changes will (most likely) be included in the next version.
 ## [Unreleased]
 - A new `ready` state is now available for arena sign templates. Signs are in this state when all players in the lobby have readied up, but the arena has not yet started due to a start delay timer. Check the wiki for details.
 - Arena signs now support dynamic list entry variables for 4 different player lists. As an example, `<notready-1>` results in the name of a player in the lobby who hasn't readied up yet. This is useful for visualizing who is holding up the lobby. Check the wiki for details.
+- Elytra are now supported chest pieces in class chests.
 - Config-files with missing `pet-items` nodes no longer errors. A missing `pet-items` node in `global-settings` is treated as empty, i.e. no pet items will be registered.
 
 ## [0.104.2] - 2020-01-03

src/main/java/com/garbagemule/MobArena/ArenaImpl.java

@@ -1189,6 +1189,7 @@ public class ArenaImpl implements Arena
                 makeUnbreakable(stack);
             }
             switch (type) {
+                case "ELYTRA":
                 case "CHESTPLATE": chestplate = stack; break;
                 case "LEGGINGS":   leggings   = stack; break;
                 case "BOOTS":      boots      = stack; break;