Update CC: Tweaked to 1.13

Look, I originally had this split into several commits, but lots of
other cleanups got mixed in. I then backported some of the cleanups to
1.12, did other tidy ups there, and eventually the web of merges was
unreadable.

Yes, this is a horrible mess, but it's still nicer than it was. Anyway,
changes:

 - Flatten everything. For instance, there are now three instances of
   BlockComputer, two BlockTurtle, ItemPocketComputer. There's also no
   more BlockPeripheral (thank heavens) - there's separate block classes
   for each peripheral type.

 - Remove pretty much all legacy code. As we're breaking world
   compatibility anyway, we can remove all the code to load worlds from
   1.4 days.
 - The command system is largely rewriten to take advantage of 1.13's
   new system. It's very fancy!

 - WidgetTerminal now uses Minecraft's "GUI listener" system.

 - BREAKING CHANGE: All the codes in keys.lua are different, due to the
   move to LWJGL 3. Hopefully this won't have too much of an impact.

   I don't want to map to the old key codes on the Java side, as there
   always ends up being small but slight inconsistencies. IMO it's
   better to make a clean break - people should be using keys rather
   than hard coding the constants anyway.

 - commands.list now allows fetching sub-commands. The ROM has already
   been updated to allow fancy usage such as commands.time.set("noon").

 - Turtles, modems and cables can be waterlogged.

src/main/java/dan200/computercraft/client/gui/GuiPrintout.java

@@ -7,13 +7,11 @@
 package dan200.computercraft.client.gui;
 
 import dan200.computercraft.core.terminal.TextBuffer;
-import dan200.computercraft.shared.media.inventory.ContainerHeldItem;
+import dan200.computercraft.shared.common.ContainerHeldItem;
 import dan200.computercraft.shared.media.items.ItemPrintout;
 import net.minecraft.client.gui.inventory.GuiContainer;
 import net.minecraft.client.renderer.GlStateManager;
-import org.lwjgl.input.Mouse;
-
-import java.io.IOException;
+import org.lwjgl.glfw.GLFW;
 
 import static dan200.computercraft.client.render.PrintoutRenderer.*;
 
@@ -41,63 +39,70 @@ public class GuiPrintout extends GuiContainer
 
         m_page = 0;
         m_pages = Math.max( m_text.length / ItemPrintout.LINES_PER_PAGE, 1 );
-        m_book = ItemPrintout.getType( container.getStack() ) == ItemPrintout.Type.Book;
+        m_book = ((ItemPrintout) container.getStack().getItem()).getType() == ItemPrintout.Type.BOOK;
     }
 
     @Override
-    protected void keyTyped( char c, int k ) throws IOException
+    public boolean keyPressed( int key, int scancode, int modifiers )
     {
-        super.keyTyped( c, k );
+        if( super.keyPressed( key, scancode, modifiers ) ) return true;
 
-        if( k == 205 )
+        if( key == GLFW.GLFW_KEY_RIGHT )
         {
-            // Right
             if( m_page < m_pages - 1 ) m_page++;
+            return true;
         }
-        else if( k == 203 )
+
+        if( key == GLFW.GLFW_KEY_LEFT )
         {
-            // Left
             if( m_page > 0 ) m_page--;
+            return true;
         }
+
+        return false;
     }
 
     @Override
-    public void handleMouseInput() throws IOException
+    public boolean mouseScrolled( double delta )
     {
-        super.handleMouseInput();
-
-        int mouseWheelChange = Mouse.getEventDWheel();
-        if( mouseWheelChange < 0 )
+        if( super.mouseScrolled( delta ) ) return true;
+        if( delta < 0 )
         {
             // Scroll up goes to the next page
             if( m_page < m_pages - 1 ) m_page++;
+            return true;
         }
-        else if( mouseWheelChange > 0 )
+
+        if( delta > 0 )
         {
             // Scroll down goes to the previous page
             if( m_page > 0 ) m_page--;
+            return true;
         }
+
+        return false;
     }
 
     @Override
-    protected void drawGuiContainerBackgroundLayer( float partialTicks, int mouseX, int mouseY )
+    public void drawGuiContainerBackgroundLayer( float partialTicks, int mouseX, int mouseY )
     {
         // Draw the printout
-        GlStateManager.color( 1.0f, 1.0f, 1.0f, 1.0f );
+        GlStateManager.color4f( 1.0f, 1.0f, 1.0f, 1.0f );
+        GlStateManager.enableDepthTest();
 
         drawBorder( guiLeft, guiTop, zLevel, m_page, m_pages, m_book );
         drawText( guiLeft + X_TEXT_MARGIN, guiTop + Y_TEXT_MARGIN, ItemPrintout.LINES_PER_PAGE * m_page, m_text, m_colours );
     }
 
     @Override
-    public void drawScreen( int mouseX, int mouseY, float partialTicks )
+    public void render( int mouseX, int mouseY, float partialTicks )
     {
         // We must take the background further back in order to not overlap with our printed pages.
         zLevel--;
         drawDefaultBackground();
         zLevel++;
 
-        super.drawScreen( mouseX, mouseY, partialTicks );
+        super.render( mouseX, mouseY, partialTicks );
         renderHoveredToolTip( mouseX, mouseY );
     }
 }