Fixed crash due to undefined classes when MineLP is not present

src/main/java/com/minelittlepony/util/render/Box.java

@@ -0,0 +1,36 @@
+package com.minelittlepony.util.render;
+
+import net.minecraft.client.model.ModelBox;
+import net.minecraft.client.model.ModelRenderer;
+
+public abstract class Box<T extends ModelRenderer> extends ModelBox {
+
+    protected final T parent;
+
+    public Box(T renderer, int texU, int texV, float x, float y, float z, int dx, int dy, int dz, float delta) {
+        super(renderer, texU, texV, x, y, z, dx, dy, dz, delta);
+        parent = renderer;
+    }
+
+    public Box(T renderer, int texU, int texV, float x, float y, float z, int dx, int dy, int dz, float delta, boolean mirror) {
+        super(renderer, texU, texV, x, y, z, dx, dy, dz, delta, mirror);
+        parent = renderer;
+    }
+
+    /**
+     * Creates a new vertex mapping the given (x, y, z) coordinates to a texture offset.
+     */
+    protected Vertex vert(float x, float y, float z, int texX, int texY) {
+        return new Vertex(x, y, z, texX, texY);
+    }
+
+    /**
+     * Creates a new quad with the given spacial vertices.
+     */
+    protected Quad quad(int startX, int width, int startY, int height, Vertex ...verts) {
+        return new Quad(verts,
+                startX,         startY,
+                startX + width, startY + height,
+                parent.textureWidth, parent.textureHeight);
+    }
+}

src/main/java/com/minelittlepony/util/render/Quad.java

@@ -0,0 +1,9 @@
+package com.minelittlepony.util.render;
+
+import net.minecraft.client.model.TexturedQuad;
+
+public class Quad extends TexturedQuad {
+    Quad(Vertex[] vertices, int texcoordU1, int texcoordV1, int texcoordU2, int texcoordV2, float textureWidth, float textureHeight) {
+        super(vertices, texcoordU1, texcoordV1, texcoordU2, texcoordV2, textureWidth, textureHeight);
+    }
+}

src/main/java/com/minelittlepony/util/render/Vertex.java

@@ -0,0 +1,19 @@
+package com.minelittlepony.util.render;
+
+import net.minecraft.client.model.PositionTextureVertex;
+
+public class Vertex extends PositionTextureVertex {
+
+    public Vertex(float x, float y, float z, float texX, float texY) {
+        super(x, y, z, texX, texY);
+    }
+
+    private Vertex(Vertex old, float texX, float texY) {
+        super(old, texX, texY);
+    }
+
+    @Override
+    public Vertex setTexturePosition(float texX, float texY) {
+        return new Vertex(this, texX, texY);
+    }
+}