fixed some potential issues with MAC addresses

added corresponding test-cases
switched to newer version of tinyxml due to some issues
adjusted affected code-parts accordingly
for better re-use, moved ceiling-calculation to a new class
some minor fixes
new helper methods
worked on wifi-opt

sensors/radio/VAPGrouper.h

@@ -7,6 +7,8 @@
 
 #include "../../math/Stats.h"
 
+#include "../../misc/Debug.h"
+
 #include "WiFiMeasurements.h"
 
 class VAPGrouper {
@@ -40,6 +42,8 @@ public:
 
 private:
 
+	static constexpr const char* name = "VAPGrp";
+
 	/** the mode to use for grouping VAPs */
 	const Mode mode;
 
@@ -85,6 +89,9 @@ public:
 
 		}
 
+		Log::add(name, "grouped " + std::to_string(original.entries.size()) + " measurements into " + std::to_string(result.entries.size()), true);
+
+
 		// done
 		return result;