Cleaning Up Mod Integrations (#2581)

* Cleaned up unused Mod integrations other than for mods that are likely to be integrated soon.
* Introduced an easier Facade class to access mod integration abstractions (called Integrations).
* Removed the link between IntegrationType and integration abstraction. Integrations are now explicitly instantiated inside of IntegrationNode.

src/main/java/appeng/integration/modules/ic2/IC2PowerSinkAdapter.java

@@ -29,6 +29,7 @@ import ic2.api.energy.prefab.BasicSink;
 import ic2.api.energy.tile.IEnergyEmitter;
 
 import appeng.api.config.PowerUnits;
+import appeng.integration.abstraction.IC2PowerSink;
 import appeng.tile.powersink.IExternalPowerSink;