Max cache option

[jwoertink]

SplayTreeMap supports a maxsize option:

stm = SplayTreeMap(String, String).new
stm.maxsize = 10

I think this just limits the number of keys you can store... Part of me thinks a file size option may be better in some cases 🤔 Like, don't let my cache go over 10mb.... I'm not sure how we could do that reliably, or efficiently, but I wanted to at least jot it down.

[jwoertink]

Coming back to this, maybe we need 2 different max cache options. A max cache entries option. This would default to unlimited, but allow you to set some value to limit the number of items that the cache can hold.

Then a secondary option which would be a memory based size, but maybe we just keep this issue specifically to the total number of entries. If anyone has a good idea on the memory size option, we can open a new issue to discuss.