This aids an API for the correlation based tracker that Davis
recently added to Dlib. I've made sure to allow overrides for
passing normal rectangles rather than drectangles (which isn't
currently supported in the Dlib C++ API). This is mostly
because I imagine people might initialize the tracking using
something like a bounding box from a detector (e.g.
load_frontal_face_detector).

The correlation tracker deals with the drectangle
(double rectangle) class which currently isn't wrapped. Therefore,
I add the drectangle class and refactor rectangles into their
own file. I also added a load of methods on rectangle that might
be useful such as intersection/contains/area etc.

The word detector didn't make much sense!

learning tools.

structural SVM solver.

a symmetric matrix was used along with the LAPACK bindings.

whenever you release the mouse button or add more points.

Fix dlib tests for c++11

c++11 std::mutex clashes with dlib::mutex when:

using namespace std;
using namespace dlib;

macros compile when invoked outside dlib namespace.

has a timeout parameter, so the connect() call should use that rather than
adding another.

rendering problem in perspective_display that appeared when drawing lines on
displays that weren't positioned at the upper left corner of the entire window.

used with objects that have non-square bounding boxes.  This has been fixed but
will cause models that were trained with the previous version of dlib to not
work as accurately if they used non-square boxes.  So you might have to retrain
your models when updating dlib.

by holding shift and right clicking and dragging.

new example code into face_detector.py and added some comments.

Merge branch 'py_det_conf_and_idx' of https://github.com/jackculpepper/dlib into jackculpepper-py_det_conf_and_idx

images.