Change to int as a default data type for bits

[gnypit]

Storing a zero as an int uses less memory compared to storing it as a str. This is because the string object has additional overhead for managing character data and string-specific metadata. Therefore, if memory efficiency is a concern, it is generally better to store numeric values as integers rather than strings.

The str approach to bits will be reserved for output purposes in the demonstrator alone. It doesn't change the fact, that wherever possible we still prefer dicts to lists, for better quality with multiple callable elements.