Only load Skopos in career games

In sandbox saves, there's no instance of `ContractSystem`. This causes a
NRE to be thrown from `Network.UpdateConnections()` in every
FixedUpdate.

With this change, Skopos doesn't get loaded in Sandbox or Science mode
save files: they don't have contracts, so Skopos wouldn't do anything
anyways.

Fixes mockingbirdnest#8

Telecom/telecom.cs

@@ -8,7 +8,8 @@
 
 namespace σκοπός {
   [KSPScenario(
-    ScenarioCreationOptions.AddToAllGames,
+    ScenarioCreationOptions.AddToNewCareerGames | ScenarioCreationOptions.AddToExistingCareerGames |
+    ScenarioCreationOptions.RemoveFromSandboxGames | ScenarioCreationOptions.RemoveFromScienceSandboxGames,
     new[] { GameScenes.SPACECENTER, GameScenes.TRACKSTATION, GameScenes.FLIGHT, GameScenes.EDITOR })]
   public sealed class Telecom : ScenarioModule, principia.ksp_plugin_adapter.SupervisedWindowRenderer.ISupervisor {