Typing Information, Frame Values in Time - type hints for all of the parameters and returns.

[Kaszanas]

Currently I am developing a library on top of moviepy.
As I go deeper into my own code I find that there is limited type information provided on the moviepy side.

I tend to have to look at the source code in order to find answers on how to properly interface with certain APIs.
In video editing there are multiple uses for creating subclips accurately up to a single frame.

Therefore I would like to propose features as follows:

1. Being able to provide the number of frame to all of the t parameters in methods such as .subclip(t_start, t_end)
2. Being able to provide the time as a float e.g. .subclip(t_start: float | int, t_end: float | int, frames:bool = False)
3. Type annotations for function / method parameters.

Conversion could be handled internally.