some fixes [multithreading,..]

needed interface changes [new options]
logger for android
wifi-ap-optimization
new test-cases

grid/GridPoint.h

@@ -67,7 +67,12 @@ struct GridPoint {
 
 
 	/** cast to string */
-	operator std::string() const {return "(" + std::to_string(x_cm) + "," + std::to_string(y_cm) + "," + std::to_string(z_cm) + ")";}
+	operator std::string() const {return asString();}
+
+	/** get as string */
+	std::string asString() const {
+		return "(" + std::to_string(x_cm) + "," + std::to_string(y_cm) + "," + std::to_string(z_cm) + ")";
+	}
 
 	/** read-only array access */
 	float operator [] (const int idx) const {
@@ -79,4 +84,16 @@ struct GridPoint {
 
 };
 
+namespace std {
+	template<> struct hash<GridPoint> {
+		int64_t operator() (const GridPoint& gp) const {
+			return
+			    (((int64_t)gp.x_cm) << 0) +
+			    (((int64_t)gp.y_cm) << 8) +
+			    (((int64_t)gp.z_cm) << 16);
+		}
+	};
+}
+
+
 #endif // GRIDPOINT_H