refactor project structure, implement tessellator

src/js/net/minecraft/util/MathHelper.js

@@ -0,0 +1,11 @@
+window.MathHelper = class {
+
+    /**
+     * Returns the greatest integer less than or equal to the double argument
+     */
+    static floor_double(value) {
+        let i = parseInt(value);
+        return value < i ? i - 1 : i;
+    }
+
+}