Add Czech language

This adds the Czech language, however for some numbers multiple options exist because some work is still needed for parsing. Work is still needed to better match the different plural cases.

For example, numbers above one million output as "milion/miliony/milionů," not taking into account the number before it, whereas one outputs "jeden/jedna/jedno" to represent all the options based on the gender of the noun. For low numbers, all options can be correct based on how the number is used, however for high numbers, only one option is correct.