[sphinx] Replace evaluation scripts and other tasks

We need to update the documentation of this package w.r.t the new evaluation scripts implemented in bob.measure. For instance, there are some references that points to bob_eval_threshold.py and such metric was replaced by bob bio .....

There are other things that should be updated in this package and they are listed below:

• replace bob_eval_threshold.py to the correspondent evaluation script in bob bio
• There are references to ./bin/ in the documentation and this should be removed
• The entry_point console scripts of this package should have some prefix. This is something that we are doing in bob.bio and in bob in general. For instance the scripts:
  • compare_rois.py should be bob_bio_vein_compare_rois.py
  • view_sample.py should be bob_bio_vein_view_sample.py
  • blame.py should be bob_bio_vein_view_blame.py
  • markdet.py should be bob_bio_vein_markdet.py
  • watershed_mask.py should be bob_bio_vein_watershed_mask.py

ping @andre.anjos