Added portal blocks to block placement. This should produce portal fragments like boobytraps that may not persist. If they don't work at all we can do it on top of an obsidian block with BlockEmbed and maybe that'll work.

Added some more spawned creatures: basic zombie, witch, pig, zombie pigman, ender dragon. Zombie is a low level attack and easy to create.  Witch is what you get from enchanting table, a nasty attack and a way to get glowstone without getting into the nether. Pig is from gold ingot so you have to find that but it's a way to not starve while mining (other good food requires you already have that food: such as Cow) and gives a clue to Gold Block, which is Zombie Pigman. Ender Dragon requires you already have the dragon egg, so it's basically an end-zone dance and there's only one dragon egg.