Add static cache for edd_get_option()

[zackkatz]

Resolves #9743

Proposed Changes:

1. Adds a static cache to edd_get_option() to improve speed.

[mbtools]

This is trading CPU for memory, which is ok. But there should be a limit to the cache size or there's trouble ahead.

[cklosowski]

Thanks @zackkatz. I'll have a look at the suggestion here and see what we can come up with. I agree that there is some precedence set that the filter will be run every time the option is getting requested...so only running the filter a single time may be a problem, but I'll see what we can do here.

I agree with @mbtools here that it's a trade in the direction of memory over CPU, which is usually a good tradeoff (but should be capped for sure).