Global code ovehaul - remove CAS and other, add 15 minute greet check

- Remove CAS, as it no longer works for us
- Remove other checks
- Implement 15 minute greet timeout check
- Fix chat logos
- Ditch thirdparty logger, use stdlib log facility wrapper for logging

internal/elog/retraction.go

@@ -0,0 +1,24 @@
+package elog
+
+import (
+	"github.com/NicoNex/echotron/v3"
+)
+
+// LogGreetingRetracted records that we deleted a greeting of our own — one the
+// addressed member never answered, because they were banned for the silence.
+//
+// The log is append-only, so the question's original line stays where it was and
+// this line says what became of it. A reader must be able to tell that the room
+// asked a question and later removed it, rather than finding a line that
+// describes a message which no longer exists.
+func LogGreetingRetracted(chat *echotron.Chat, user *echotron.User, messageID int) {
+	if _, on := chatLogRoot(); !on || chat == nil {
+		return
+	}
+
+	body := "greeting " + itoaInt(messageID) + " retracted, member banned without answering"
+
+	appendLine(chat.ID, renderLine(*chat, user, body))
+}
+
+/* vim: set ft=go noet ai ts=4 sw=4 sts=4: */