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

Resources/Textures/Objects/markers.rsi/meta.json

@@ -0,0 +1 @@
+{"version": 1, "size": {"x": 32, "y": 32}, "license": "CC-BY-SA-3.0", "copyright": "Taken from https://github.com/vgstation-coders/vgstation13/blob/e71d6c4fba5a51f99b81c295dcaec4fc2f58fb19/icons/mob/screen1.dmi", "states": [{"name": "cross_blue", "directions": 1, "delays": [[1.0]]}, {"name": "cross_green", "directions": 1, "delays": [[1.0]]}, {"name": "cross_red", "directions": 1, "delays": [[1.0]]}]}