Resolve "Adapt to const nonconst new API"

Closes #22 (closed)

include/laser/capture/capture_laser_2d.h

@@ -47,6 +47,7 @@ class CaptureLaser2d : public CaptureBase
         CaptureLaser2d(const TimeStamp& _ts, SensorBasePtr _sensor_ptr, const std::vector<float>& _ranges);
         ~CaptureLaser2d() override = default;
 
+        const laserscanutils::LaserScan& getScan() const;
         laserscanutils::LaserScan& getScan();
 
         void setSensor(const SensorBasePtr sensor_ptr) override;
@@ -57,6 +58,11 @@ class CaptureLaser2d : public CaptureBase
 
 };
 
+inline const laserscanutils::LaserScan& CaptureLaser2d::getScan() const
+{
+    return scan_;
+}
+
 inline laserscanutils::LaserScan& CaptureLaser2d::getScan()
 {
     return scan_;