refactor so I can track and ignore recent packets of any type

src/mesh/PacketHistory.h

@@ -0,0 +1,33 @@
+#pragma once
+
+#include "Router.h"
+#include <vector>
+
+/**
+ * A record of a recent message broadcast
+ */
+struct PacketRecord {
+    NodeNum sender;
+    PacketId id;
+    uint32_t rxTimeMsec; // Unix time in msecs - the time we received it
+};
+
+/**
+ * This is a mixin that adds a record of past packets we have seen
+ */
+class PacketHistory
+{
+  private:
+    /** FIXME: really should be a std::unordered_set with the key being sender,id.
+     * This would make checking packets in wasSeenRecently faster.
+     */
+    std::vector<PacketRecord> recentPackets;
+
+  public:
+    PacketHistory();
+
+    /**
+     * Update recentBroadcasts and return true if we have already seen this packet
+     */
+    bool wasSeenRecently(const MeshPacket *p);
+};