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/run

@@ -7,7 +7,7 @@
 # rproxy asks it there unless SWW_RPROXY_WAF_BACKEND says otherwise. Unless
 # SWW_WAF_STATE_DIR is set, the state files go in bin/state, beside the binary,
 # and unless SWW_WAF_CACHE_DIR is set, the cache files go in bin/cache. Unless
-# SWW_WAF_RULES_DIR is set, the rule files are those of share/rules.d, which the
+# SWW_WAF_RULE_FILES_DIR is set, the rule files are those of share/rules.d, which the
 # image ships.
 set -eu
 
@@ -37,9 +37,9 @@ main() {
         export SWW_WAF_CACHE_DIR
         mkdir -p "$SWW_WAF_CACHE_DIR"
     fi
-    if [ -z "${SWW_WAF_RULES_DIR+set}" ]; then
-        SWW_WAF_RULES_DIR="$ROOT/share/rules.d"
-        export SWW_WAF_RULES_DIR
+    if [ -z "${SWW_WAF_RULE_FILES_DIR+set}" ]; then
+        SWW_WAF_RULE_FILES_DIR="$ROOT/share/rules.d"
+        export SWW_WAF_RULE_FILES_DIR
     fi
     SWW_WAF_LISTEN_ADDR="${SWW_WAF_LISTEN_ADDR:-:8090}"
     SWW_RPROXY_WAF_BACKEND="${SWW_RPROXY_WAF_BACKEND:-http://127.0.0.1:${SWW_WAF_LISTEN_ADDR##*:}}"