Added Czech bank account numbers

[petrprikryl]

#295

[arthurdejong]

Hi @petrprikryl,

Thanks for the PR. I've merged it as c5595c7 with a few small modifications. Some things could be simplified a bit and I've moved the zero padding to the compact() function. It strictly speaking doesn't make the number more compact but at least it ensures a consistent representation of the number (another approach would have been to trim leading zeros if possible).