Increase the number of allowed pipe connection categories

[asher_sky]

Please consider increasing the number of allowed connection_category. Currently, if you load the game with the Py mod, add a pipe (and underground) for each fluid, and give each pipe a unique category so it doesn't connect to pipes for other fluids, the game errors on load, complaining about too many categories.

I did not find any mention of this limit in the documentation, so it may also be worth mentioning that there is a limit.

[boskid]

For 2.0.21 i changed connection_category to accept more than 64 unique categories.