Handle managing computer inputs/outputs separatly

The Computer class currently has several resposiblities such as storing
id/label, managing redstone/peirpherals, handling management of the
computer (on/off/events) and updating the output.

In order to simplify this a little bit, we move our IAPIEnvironment
implementation into a separate file, and store all "world state"
(redstone + peripherals) in there. While we still need to have some
level of updating them within the main Computer instance, it's
substantially simpler.

src/main/java/dan200/computercraft/shared/common/BlockGeneric.java

@@ -51,6 +51,7 @@ public abstract class BlockGeneric extends Block implements ITileEntityProvider
 
     @Override
     @Deprecated
+    @SuppressWarnings( "deprecation" )
     public final void neighborChanged( IBlockState state, World world, BlockPos pos, Block block, BlockPos neighbour )
     {
         TileEntity tile = world.getTileEntity( pos );