ORB-SLAM3

Details of changes between the different versions.

RGB-D compatibility, the RGB-D examples had been adapted to the new version.
Kitti and TUM dataset compatibility, these examples had been adapted to the new version.
ROS compatibility, It had been updated the old references in the code to work with this version.
Config file parser, the YAML file contains the session configuration, a wrong parametrization may break the execution without any information to solve it. This version parses the file to read all the fields and give a proper answer if one of the fields have been wrong deffined or don't exist.
Fixed minor bugs.

Initial release. It has these capabilities:

Multiple-Maps capabilities, it is able to handle multiple maps in the same session and merge them when a common area is detected with a seamless fussion.
Inertial sensor, the IMU initialization takes a 2 seconds to achieve a scale error less than 5\% and it is reffined in the next 10 seconds until is around 1\%. Inertial measures are integrated at frame rate to estimate the scale, gravity and velocity in order to improve the visual features detection and make the system robust to temporal occlusions.
Fisheye sensor, the fisheye sensors are now fully supported in monocular and stereo.