Rename the settings whose names do not say what they control (closes #234)

Applies the setting renames of the naming audit under the SWW_WAF_ and
SWW_RPROXY_ prefixes, with sneak's names for the IP reputation cache
time and the two time limits, which now take milliseconds. The rproxy
log field default_disposition becomes waf_backend_no_answer, and
config.Config and config.FromEnvironment become config.WAF and
config.WAFFromEnvironment. Go fields, test names and prose follow. No
aliases; nothing reads the old names.

Model: opus-5-5

docs/metrics.md

@@ -6,7 +6,7 @@ the `instance` label as `exported_instance` unless the scrape sets
 `honor_labels: true`. `rproxy` has no metrics.
 
 Every `sww_*request_bytes_total` and `sww_*response_bytes_total` series counts
-body bytes, never headers, whatever `SWW_WAF_BYTES_COUNT` says.
+body bytes, never headers, whatever `SWW_WAF_BYTES_COUNTED` says.
 
 ## Traffic
 
@@ -33,7 +33,8 @@ body bytes, never headers, whatever `SWW_WAF_BYTES_COUNT` says.
 
 ## Countries and AS numbers
 
-For the `SWW_WAF_METRICS_TOP_N` busiest of each, the rest as `other`:
+For the `SWW_WAF_METRICS_BUSIEST_COUNTRIES_AND_ASNS` busiest of each, the rest
+as `other`:
 
 - `sww_country_requests_total`, `sww_country_request_bytes_total`,
   `sww_country_response_bytes_total` and `sww_country_list_refusals_total`, by