Implement first pass at config loading, /join, /leave commands, tab completion (broken)

src/main/resources/config.yml

@@ -0,0 +1,16 @@
+maps:
+  quarry:
+    target:
+      x: -20.0
+      y: 80.0
+      z: 31.0
+    spawnpoints:
+      - x: -15.0
+        y: 80.0
+        z: -46.0
+      - x: -1.0
+        y: 80.0
+        z: -45.0
+      - x: 12.0
+        y: 81.0
+        z: -42.0

src/main/resources/plugin.yml

@@ -4,11 +4,17 @@ api-version: 1.18
 main: gg.malloc.defense.Plugin
 depend:  []
 commands:
+  ready:
+    description: Mark yourself as ready for the next wave
+  list:
+    description: List games
+  join:
+    description: Join a game
+  leave:
+    description: Leave a game
   setstage:
     description: Sets a game stage
   addplayer:
     description: Adds a player to a game
   debuginfo:
     description: Unknowable powers
-  ready:
-    description: Mark yourself as ready for the next wave