marker creators utility

[sarthou]

This pull request does not affect the classic behavior of ar_track_alvar but adds two utilities that allow you to simply create remote markers (on XYZ) and cubes with six markers.

Based on sampleMarkerCreator, it generates the PNG and XML files with the corresponding transformations.

In addition, it allows users to create color markers for more diversity.

A readme file explaining the use of the utility is present in the folder ar_track_alvar

⚠️ This pull request will only affect the ABI to fix some minor bugs and remove a lot of warnings.

⚠️ This pull request also deletes a lot of unnecessary spaces and cleans the code by using a good indentation.