checking for particular errors. curl/curl.h defines the errros

sized buffer that may be passed to a write callback

CURLINFO_REDIRECT_TIME and CURLINFO_REDIRECT_COUNT.

or not

CURLOPT_DEBUGFUNCTION and CURLOPT_DEBUGDATA.

## operator)

with a #define to preserve backwards compatibiltiy

The default cache timeout for this is 60 seconds, which is arbitrary and
completely subject to change :)

    - Use a global dns cache (via setting the tentatively named,
    CURLOPT_DNS_USE_GLOBAL_CACHE option to true)
    - Use a per-handle dns cache, by default
    - Use a pooled dns cache when in the "multi" interface