Implemented trapped chests & others

+ Added trapped chests
* Fixed a bunch of bugs in the redstone simulator concerning wires and
repeaters
* Other potential bugfixes

With thanks.
Yet repeaters do not power off instantly but are determined by their block type. To avoid prematurely removing their entry, more code is needed.

Why not do this, as well as fixing the wires, in another pull request? If we should change the way power is removed, the conditions in RedstoneAddBlock will have to be removed as well, and you said yourself that I should split unrelated stuff. The function name 'SetSourceUnpowered' and the PR name 'trapped chests' certainly don't say anything on a redstone refactor! :D