Refactor to only support fiddy.function.Function-type functions, and store history

[dilpath]

Store each function call as a dataclass object, and the history would be a list of such objects.

Only support fiddy.function.Function so history can be automatically generated inside __call__.

Pros:

• can be used as a cache
  • either remove fiddy.function.CachedFunction, or disable history if CachedFunction is used
    • caching user option as a fiddy.function.Function attribute (e.g. boolean save_history and history_as_cache)
• can be easily converted to a human-readable format e.g. pandas DataFrame
  • and store/load history (cache) as a DataFrame
• easy to query results and reuse, if a DataFrame

Cons:

• speed
  • need to limit slow pandas operations such as append
  • may be slower than the current disk or ram caching (can support all caching options)