renamed the objects and generally improved documentation.

Also added an operator<< for dnn_trainer that prints the parameters it's using.

These changes also break backwards compatibility with the previous
serialization format for dnn_trainer objects.

checks if the user is giving truth boxes that can't be detected because the
non-max suppression settings would prevent them from being output at the same
time.  If this happens then we print a warning message and set one of the
offending boxes to "ignore".

code from java.

libpng than they built against.

member area of the class.  This way, we avoid a potential error where the
buffers are reallocated while cuDNN is still using them in the background.

* added shared workspace

* rewrite shared workspace code

* rename and device-based buffer allocation

* fix cudnn_device_buffer constructors

next using dlib::correlation_tracker.

* Make http_client compile in C++11 and above

* Optimize file reading

* Add per-pixel mean square loss

* Add documentation of loss_mean_squared_per_pixel_

* Add test case for per-pixel mean square loss: a simple autoencoder

* Review fix: reorder params of function tensor_index, so that the order corresponds to the convention used in the rest of the dlib code base

* Review fix: add breaks as intended, and change the rest of the test accordingly

* Again a case where the tests already work locally for me, but not on AppVeyor/Travis - this commit is a blindfolded attempt to fix the problem
(and it also fixes a compiler warning)