Rotate modem models 180 degrees

Or pi radians. Or tau/2 radians.

This ensures the main modem texture is facing towards the screen.

src/main/resources/assets/computercraft/models/block/modem.json

@@ -16,5 +16,37 @@
                 "east":  { "uv": [ 13, 2, 16, 14 ], "texture": "#front" }
             }
         }
-    ]
+    ],
+    "display": {
+        "gui": {
+            "rotation": [ 30, 45, 0 ],
+            "translation": [ 3.2, -2, 0],
+            "scale":[ 0.75, 0.75, 0.75 ]
+        },
+        "ground": {
+            "rotation": [ 0, 0, 0 ],
+            "translation": [ 0, 3, 0],
+            "scale":[ 0.25, 0.25, 0.25 ]
+        },
+        "fixed": {
+            "rotation": [ 0, 0, 0 ],
+            "translation": [ 0, 0, 0],
+            "scale":[ 0.5, 0.5, 0.5 ]
+        },
+        "thirdperson_righthand": {
+            "rotation": [ 75, 180, 0 ],
+            "translation": [ 0, 2.5, 0],
+            "scale": [ 0.375, 0.375, 0.375 ]
+        },
+        "firstperson_righthand": {
+            "rotation": [ 0, 45, 0 ],
+            "translation": [ 0, 0, 0 ],
+            "scale": [ 0.40, 0.40, 0.40 ]
+        },
+        "firstperson_lefthand": {
+            "rotation": [ 0, 45, 0 ],
+            "translation": [ 0, 0, 0 ],
+            "scale": [ 0.40, 0.40, 0.40 ]
+        }
+    }
 }