implement < operator for signal to be able to sort them

Author: Murmele

include/libdbc/signal.hpp

@@ -25,6 +25,7 @@ namespace libdbc {
 		explicit Signal(std::string name, bool is_multiplexed, uint32_t start_bit, uint32_t size, bool is_bigendian, bool is_signed, double factor, double offset, double min, double max, std::string unit, std::vector<std::string> recievers);
 
 		virtual bool operator==(const Signal& rhs) const;
+        bool operator< (const Signal& rhs) const;
 	};
 
 	std::ostream& operator<< (std::ostream &out, const Signal& sig);

src/signal.cpp

@@ -12,6 +12,9 @@ namespace libdbc {
 			   (this->unit == rhs.unit) && (this->receivers == rhs.receivers);
 	}
 
+    bool Signal::operator< (const Signal& rhs) const {
+        return start_bit < rhs.start_bit;
+    }
 
 	std::ostream& operator<< (std::ostream &out, const Signal& sig) {
 		out << "Signal {name: " << sig.name << ", ";