Not sure which of the other classes matching *TreeProcessor need an alias too, just let me know, and I'll update accordingly.

I'm inclined to not merge this as the current capitalization matches the other classes (preprocessor, postprocessor, etc.). Anyone else have any thoughts?

FYI, BlockProcessor is an outlier: https://github.com/Python-Markdown/markdown/blob/master/markdown/blockprocessors.py#L59. I'm not sure which way you'd like to normalize class names 🤷🏻.

So it would appear that for the least amount of change we would change BlockProcessor => Blockprocessor, which would result in a consist style.

If we went the other way, we would need to change everything except BlockProcessor. Although, I can see an argument for not camel casing Preprocessor as that would be a single work in normal English prose. I suspect that is where the current style of not camel casing any of them case from. BlockProcessor was certainly a later addition and perhaps we forgot about that earlier style choice.

I'm fine either way, I've now also created #1290 that changes spelling for the BlockProcessor to Blockprocessor