Add ItemBook property

After trying to figure out how to make the book info work without
creating weird errors with the pipe symbols and newlines, I decided to
use an HTML-style escape system for book meta.
Works extremely well!

- Also, fix some errors in RuntimeCompiler.
Add speed argument to the shoot command

Because the default physics aren't all that impressive... shooting in an
arbitrary direction and speed is useful.
Calculate particle effects correctly

the Effects enum sometimes acts like it has effects it doesn't... no
idea what's going on there, just give it a lowered priority under
ParticleEffect for now.