Caches of outside APIs live in /var/cache/sww (closes #314)

The answers of GeoJS, the lists fetched by URL, the DNS blocklists and
AbuseIPDB each go in a cache file in SWW_CACHE_DIR (default
/var/cache/sww): lookups.json, lists.json, dnsbl.json and
abuseipdb-scores.json. reputation.json is gone. The AbuseIPDB checks
spent today are a count, not a cache, and stay in SWW_STATE_DIR as
abuseipdb-checks.json.

A cache file never stops the start: one that does not parse is set
aside as an edit is, one that cannot be read is written over, and its
cache starts empty. An unwritable SWW_CACHE_DIR stops the start, as an
unwritable SWW_STATE_DIR does. The run script makes the cache directory
and gives it to sww.

Model: opus-5-5

internal/reputation/dnsbl_test.go

@@ -389,7 +389,7 @@ func TestVerdictsKeptAcrossARestart(t *testing.T) {
 			t.Errorf("verdicts %+v, want %+v", kept, want)
 		}
 
-		// Restarted an hour later with what reputation.json keeps, it uses
+		// Restarted an hour later with what dnsbl.json keeps, it uses
 		// the verdicts, and asks the zone nothing, until the TTL has passed
 		// since they were fetched.
 		time.Sleep(time.Hour)
@@ -446,7 +446,7 @@ func TestAtMost100000VerdictsKeptTheOneFetchedLongestAgoDroppedFirst(t *testing.
 	p.Now = func() time.Time { return now }
 	dnsbl := reputation.NewDNSBL(p)
 
-	// 100,001 verdicts, listed by client, as reputation.json lists them,
+	// 100,001 verdicts, listed by client, as dnsbl.json lists them,
 	// each fetched a millisecond before the one before it: the last is one
 	// too many.
 	const count = 100001