Stringifiable and TextFile

[logicplace]

Depends on: #4

TextFile is the stringifiable version of BinaryFile

Stringifiable subclasses must implement the methods:

• stringify(self) -> str
• parse(self, string: str)

Any keyword-only arguments defined in these are keys to pull, like in calculations.

While it would be nice if parse accepted a buffer instead, and read until it was done (rather than necessarily the whole thing), I don't think this is reasonably possible to do. If a method of making it reasonable is discovered, it would be nice, though!! Thus, neither of these have alternative prototypes, but still need to be decorated to handle the key pulling.