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/offline/FileReader.h

@@ -193,7 +193,8 @@ namespace Offline {
 			WiFiMeasurements wifi;
 			Splitter s(data, sep);
 
-			for (size_t i = 0; i < s.size(); i += 3) {
+			// the -1 is due to some old files containing a trailing ";" resulting in one additional stray column
+			for (size_t i = 0; i < s.size()-1; i += 3) {
 
 				const std::string mac = s.get(i+0);
 				const float freq = s.getFloat(i+1);