[gdal_tindex] Use argparser

[elpaso]

No description provided.

[rouault]

Do you mind reworking the commit history in 4 separate commits?:

• change to argparse.hpp
• addition of the new method in gdalargumentparser.h/cpp
• use of this new method in the already converted utilities (I wouldn't mind if it is merged in the previous commit)
• changes to gdaltindex_bin/_lib

[elpaso]

Do you mind reworking the commit history in 4 separate commits?:

* change to argparse.hpp

* addition of the new method in gdalargumentparser.h/cpp

* use of this new method in the already converted utilities (I wouldn't mind if it is merged in the previous commit)

* changes to gdaltindex_bin/_lib

done

[coveralls]

coverage: 69.08% (+0.005%) from 69.075%
when pulling 67ff7ba on elpaso:gdaltindex-argparse
into 5dfa73a on OSGeo:master.