Could you please make MAX_CHUNK configurable?

[JasonShui716]

When we used the hyper lib on a ARM board with Python 3.7.3, we found that our program could run MUCH MUCH faster by increasing the MAX_CHUNK from 1024 to 1024 * 16. You can give it a default value - that's not bad, but could you please also provide it as a configurable variable so that we can config it out of the lib and earn more benefit? Thx! Hoping for your response.

[JasonShui716]

@njsmith @sethmlarson Many thanks.