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

script/example-app

@@ -214,8 +214,8 @@ main() {
     wait_for "waf did not stop in order" logged "$WAF" '"msg":"stopped"'
     [ "$(status_from 203.0.113.9 /)" = 200 ] ||
         fail "with waf stopped, the app did not answer through rproxy"
-    wait_for "rproxy logged no request SWW_RPROXY_DEFAULT_DISPOSITION decided" \
-        logged "$APP" '"default_disposition":true'
+    wait_for "rproxy logged no request SWW_RPROXY_WAF_BACKEND_NO_ANSWER_DISPOSITION decided" \
+        logged "$APP" '"waf_backend_no_answer":true'
     docker exec "$APP" /usr/local/bin/sww healthcheck ||
         fail "with waf stopped, the app's health check failed"
     echo "example-app: with waf stopped, the app answers through rproxy"