Use ROI selector in python samples

This contribution changes the way how trackers should be implemented by
programmer. It should be noted first, that from the user prospective,
Tracker::create() method still can be called with the same effect.
However, there's no more thing as a "constructor" for Tracker, they
should be created via static functions, e.g.
    static Ptr<TrackerMIL> createTracker(const TrackerMIL::Params &parameters=TrackerMIL::Params());

From the programmer's perspective now for every tracker what is declared
in tracker.hpp header is more a "interface", while the real
implementation class can (and has to) be implemented in .cpp file.

Changes in documentation are also included.

I've changed Rect to Rect2d in Tracker::update(), Tracker::init() and
all related methods (including documentation). This allows to initialize
trackers with double-valued rectangles, thus adding versality. Besides,
trackers also can output double-valued rectangles, which may be
beneficial in some scenarios.

However, it remains to change UML diagrams in documentation to tracker
module, as they still display methods above with old signatures.

Added OPE tests tracking

- Reinitialized random number generator (TrackerMIL and TrackerBoosting)
- Removed unused meanSigmaPair

Changed sample tracker.cpp with a list of images instead the video file

Modified OPE tests tracking

- The overlap threshold varies from 0.0 to 1.0
- The location error threshold varies from 0 to 50

Changed name for the tests

Removed unused field

Enlarged first rect of 10% respect the ground truth

Added TRE test

TRE test for the temporal robustness evaluation

Added SRE Test (spatial robustness evaluation)

- Removed the enlargment of the first frame
- TRE corrected the computation of the distance and the overlap
- TrackerBoosting changed the search factor

Fixed last segment in test TRE

First stub for regression test

Added test for faceocc2

Added perf_test for mil and boosting trackers

Modified SANITY_CHECK with ERROR_RELATIVE

In xml generated added the ratio between of the correct bounding box (based on dynamic threshold)

OPE Test: works with video and not with sequence of images

TRE Test: works with video and not with sequence of images

SRE Test: works with video and not with sequence of images

Perf test: works with video and not with sequence of images

Removed unused file

sample tracker.cpp: works with video and not with sequence of images

Modified Copyrights

Moved plantuml source files under doc

disabled tests

Added include of precomp.hpp