Spawn point system.

Hey we can place spawn points on the map now instead of hardcoding them!
Spawn points are simply invisible bare bones entities.

Resources/Prototypes/Entities/markers/spawn_points.yml

@@ -0,0 +1,31 @@
+- type: entity
+  name: Spawn Point
+  id: spawn_point
+  abstract: true
+  components:
+  - type: Sprite
+    netsync: false
+    visible: false
+    sprite: Objects/markers.rsi
+
+  - type: Icon
+    sprite: Objects/markers.rsi
+
+  - type: SpawnPoint
+
+  placement:
+    mode: SnapgridCenter
+
+- type: entity
+  name: LateJoin Spawn Point
+  id: spawn_point_latejoin
+  parent: spawn_point
+  components:
+  - type: Sprite
+    state: cross_red
+
+  - type: SpawnPoint
+    spawn_type: LateJoin
+
+  - type: Icon
+    state: cross_red