Add MKL DFTI FFT bindings.

Apparently, MKL installations don't always include header files. So
detect MKL libraries and headers seperately.

feature_addition : Added a mean squared loss layer to DNN with test case

MKL FFT bindings had assumed that MKL was also being used to provide the
BLAS implementation, however the build system allows these 2 things to
be configured independantly.

Added mean squared loss layer "loss_mean_squared" to
DNN as requested in https://github.com/davisking/dlib/issues/152
Also added test case of a simple linear regression with one variable
that uses this layer.

unicode: Disable misleading-indentation warnings with GCC pragma

increasing loss more robust.  Now it will never get into a situation where it
backtracks over and over.  Instead, it will only backtrack a few times in a row
before just letting SGD run unimpeded.

reachable.

Remove initializer lists support for Apple/Clang (libstdc++ version used does not include std::initializer_list) (#334)

Remove initializer lists support for Apple/Clang (libstdc++ version used does not include std::initializer_list)

* Expose python binding for running multiple detectors at once

* Remove unwanted typedef

Modify to support both train-images-idx3-ubyte and train-images.idx3-ubyte styles of the filename. (#327)

* Add option --rm-other-labels to imglab

* Add support for comma separated list of labels