phraser, mavend: read the fallbacks from the file (V-501)

The accessors are functions now, so the call sites that compared against one
literal compare against the entry instead: IsUnknownFallback and
IsSourcesFallback in the daemon tests, the entry key in the phraser tests. A
reworded variant no longer breaks a Go test.

The eval scores every variant on the persona checks the nudges already pass.

cmd/mavend/worldmodel_test.go

@@ -35,7 +35,7 @@ func TestQueryGeneralNamesTheGap(t *testing.T) {
 	if !ok {
 		t.Fatal("queryGeneral passed on the last source in the chain")
 	}
-	if reply != worldGap {
+	if reply != worldGap() {
 		t.Fatalf("reply = %q, want the named gap", reply)
 	}
 	if g.worldCalls != 1 {
@@ -51,7 +51,7 @@ func TestQueryGeneralWithoutAWorldModelIsUnchanged(t *testing.T) {
 	if !ok {
 		t.Fatal("queryGeneral passed on the last source in the chain")
 	}
-	if reply != "не знаю." {
+	if !phraser.IsUnknownFallback(reply) {
 		t.Fatalf("reply = %q, want the Stub's answer", reply)
 	}
 }
@@ -61,12 +61,12 @@ func TestQueryGeneralWithoutAWorldModelIsUnchanged(t *testing.T) {
 // English in it.
 func TestWorldGapIsInPersona(t *testing.T) {
 	for _, bad := range []string{"вы", "ваш", "рад ", "дорогой", "милый"} {
-		if strings.Contains(worldGap, bad) {
-			t.Errorf("the gap phrase contains %q: %s", bad, worldGap)
+		if strings.Contains(worldGap(), bad) {
+			t.Errorf("the gap phrase contains %q: %s", bad, worldGap())
 		}
 	}
-	if strings.ContainsAny(worldGap, "abcdefghijklmnopqrstuvwxyz") {
-		t.Errorf("the gap phrase has Latin letters in it: %s", worldGap)
+	if strings.ContainsAny(worldGap(), "abcdefghijklmnopqrstuvwxyz") {
+		t.Errorf("the gap phrase has Latin letters in it: %s", worldGap())
 	}
 }