added helper methods for debug printing

fixed issue when reading wifi entries within old walk files
worked on earth-registration
added corresponding test-cases
other minor changes

sensors/radio/setup/WiFiOptimizer.h

@@ -32,6 +32,13 @@ namespace WiFiOptimizer {
 			return res;
 		}
 
+		/** get all [VAPGrouped, Averaged] fingerprints for the given mac */
+		virtual const std::vector<RSSIatPosition>& getFingerprintsFor(const MACAddress& mac) {
+			const auto& it = apMap.find(mac);
+			if (it == apMap.end()) {throw Exception("mac not found: " + mac.asString());}
+			return it->second;
+		}
+
 		/** add a new fingerprint to the optimizer as data-source */
 		virtual void addFingerprint(const WiFiFingerprint& fp) {