CameraRealSense2: added new warnings to debug easier timestamps problems.
GUI: added gravity visualization.
DbViewer: empty clouds in OctoMap mode have color depending on probability of occupancy.
Brought general changes from local xvision branch.
-CreateSimpleCalibrationDialog updated to create mono/stereo calibration files with advanced option (setting intrinsics of each camera + extrinsics between them). Rectification R and new camera P matrices are then automatically computed.
-Added GeodeticCoords class for convience conversion between GPS values (latitude/longitude/altitude) to local coordinate (ENU).
-Added support of Malaga Urban and St Lucia ground truths.
-CameraImages: added option to debayer images. Timestamps file: added support of "sec millisec" format.
-Added UException class: exceptions are sent instead of exiting the application on UASSERT or UFATAL.