Cache modes

[g105b]

The init parameter "cache" specifies one of the following cache modes:

• default
• no-store
• reload
• no-cache
• force-cache
• only-if-cached

See: https://developer.mozilla.org/en-US/docs/Web/API/Request/cache

Currently, there is no cache mechanism built into the library. Maybe this should be part of PHP.Gt/Curl instead?