Feature request: Add `scale=dict(level=my_level)` support

[Leengit]

A number of methods accept scale=dict(magnification=my_magnification) as a parameter. This issue requests that those methods also accept scale=dict(level=my_level). Here level is as in: my_level = ts.getLevelForMagnification(my_magnification, rounding=False).

This functionality is straightforward, helpful, and unlikely to be misunderstood. By having this functionality, we could save a day of debugging for people like me who might assume that the functionality has been present all along. (Resemblance to actual events is coincidental!)

If this feature is not added, please consider returning an error for attempting to use this feature.

Thank you