Added ability to lock machines and configure a whitelist for them

Also included are a few smaller fixes and improvements:
- Added a proper GUI for the machine view
- Fixed more MipMap flickering issues when viewing machine contents

Fixes #228

Author: davenonymous

src/main/java/org/dave/compactmachines3/block/BlockMachine.java

@@ -283,7 +283,7 @@ public void onBlockPlacedBy(World world, BlockPos pos, IBlockState state, Entity
                 tileEntityMachine.setCustomName(stack.getDisplayName());
             }
 
-            if(stack.getTagCompound().hasKey("owner")) {
+            if(stack.getTagCompound().hasKey("ownerLeast") && stack.getTagCompound().hasKey("ownerMost")) {
                 tileEntityMachine.setOwner(stack.getTagCompound().getUniqueId("owner"));
             }
         }
@@ -317,7 +317,7 @@ public boolean onBlockActivated(World world, BlockPos pos, IBlockState state, En
         }
 
         ItemStack playerStack = player.getHeldItemMainhand();
-        if(!playerStack.isEmpty()) {
+        if(!playerStack.isEmpty() && machine.isAllowedToEnter(player)) {
             Item playerItem = playerStack.getItem();
 
             // TODO: Convert the ability to teleport into a machine into an itemstack capability
@@ -340,6 +340,11 @@ public boolean onBlockActivated(World world, BlockPos pos, IBlockState state, En
                 TeleportationTools.teleportPlayerToMachine((EntityPlayerMP) player, machine);
                 StructureTools.setBiomeForCoords(machine.coords, world.getBiome(pos));
 
+                if(!machine.hasOwner() || "Unknown".equals(machine.getOwnerName())) {
+                    machine.setOwner(player);
+                    machine.markDirty();
+                }
+
                 return true;
             }
         }

src/main/java/org/dave/compactmachines3/gui/GUIHelper.java

@@ -0,0 +1,37 @@
+package org.dave.compactmachines3.gui;
+
+import net.minecraft.client.renderer.BufferBuilder;
+import net.minecraft.client.renderer.Tessellator;
+import net.minecraft.client.renderer.vertex.DefaultVertexFormats;
+
+public class GUIHelper {
+    public static void drawStretchedTexture(int x, int y, int width, int height, int textureX, int textureY, int textureWidth, int textureHeight) {
+        float f =  0.00390625F;
+        double zLevel = 0.0f;
+
+        Tessellator tessellator = Tessellator.getInstance();
+        BufferBuilder bufferbuilder = tessellator.getBuffer();
+        bufferbuilder.begin(7, DefaultVertexFormats.POSITION_TEX);
+        bufferbuilder
+                .pos((double)(x + 0), (double)(y + height), zLevel)
+                .tex((double)((float)(textureX + 0) * f), (double)((float)(textureY + textureHeight) * f))
+                .endVertex();
+
+        bufferbuilder
+                .pos((double)(x + width), (double)(y + height), zLevel)
+                .tex((double)((float)(textureX + textureWidth) * f), (double)((float)(textureY + textureHeight) * f))
+                .endVertex();
+
+        bufferbuilder
+                .pos((double)(x + width), (double)(y + 0), zLevel)
+                .tex((double)((float)(textureX + textureWidth) * f), (double)((float)(textureY + 0) * f))
+                .endVertex();
+
+        bufferbuilder
+                .pos((double)(x + 0), (double)(y + 0), zLevel)
+                .tex((double)((float)(textureX + 0) * f), (double)((float)(textureY + 0) * f))
+                .endVertex();
+
+        tessellator.draw();
+    }
+}