Add matplotlib as a test and an optional dependency

See merge request !10

Docs url fix

See merge request !7

removed unnecessary commands starting with ./bin/

See merge request !5

[doc] change the title of the guide

See merge request !4

Implemented a better way to handle group multiple detections than a simple pruning

I have implemented a better way to incorporate several detections using ``detect_all_faces``. 

When a single face should be detected, it merges all overlapping detected bounding boxes that are over threshold into one single bounding box.
In the old way, when multiple faces should be detected, for overlapping detected bounding boxes, only the one with the highest detection value was returned.

In the new version, also for multiple faces, overlapping bounding boxes are merged into one, similar to the single face case.

@andre.anjos, @tiago.pereira, @amohammadi : Could you please check this?

See merge request !1

Implemented a better way to handle group multiple detections than a simple pruning (mostly copied from the 'color' branch)

Fix outdated documentation

Fixes #6 

See merge request !3