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

Dockerfile

@@ -226,7 +226,7 @@ RUN groupadd --system --gid 65532 sww \
 # script makes SWW_WAF_STATE_DIR if it is missing and gives it to the sww user.
 RUN mkdir /var/lib/sww
 
-# The default rule file, in SWW_WAF_RULES_DIR by default, where a Dockerfile
+# The default rule file, in SWW_WAF_RULE_FILES_DIR by default, where a Dockerfile
 # built FROM this image can copy rule files of its own beside it.
 COPY share/rules.d/00-default.rules /etc/sww/rules.d/00-default.rules