ProcessorTracker: max_new_features

Created by: joanvallve

Currently, this parameter is an unsigned int atribute in ProcessorTracker. It is used when it calls the method detectNewFeatures(max_new_features) in the derived classes.

Until now, 0 meant unlimited number of new features allowed to be detected.

However, now I realize that there are some cases in which no new features should be detected (localization without mapping, for instance) so 0 value shouldn't mean unlimited.

Should we change it to an integer and use -1 to unlimited or do you think it would be better to stay with an unsigned int and put a huge number when we want unlimited amount of new features?