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

internal/rproxy/question_test.go

@@ -407,7 +407,7 @@ func TestAMethodNotPassedOnIsAnswered405(t *testing.T) {
 
 			line := out.requestLine(t)
 			if line["status"] != float64(http.StatusMethodNotAllowed) ||
-				line["disposition"] != nil || line["default_disposition"] != nil {
+				line["disposition"] != nil || line["waf_backend_no_answer"] != nil {
 				t.Errorf("line %v, want status 405 and no disposition", line)
 			}
 
@@ -490,7 +490,7 @@ func TestARequestThatCannotGoToWAFAsSentIsRefused(t *testing.T) {
 
 			line := out.requestLine(t)
 			if line["status"] != float64(http.StatusBadRequest) ||
-				line["disposition"] != nil || line["default_disposition"] != nil {
+				line["disposition"] != nil || line["waf_backend_no_answer"] != nil {
 				t.Errorf("line %v, want status 400 and no disposition", line)
 			}