removed original samples and replace them with new ones. modified new samples (reduce code duplication, add cmd line params and short description)

when true, use signed gradient for the angular histogram computation.
default to false for backward compatibility.

A define was forgotten for the codecs and there was a typo for
another.

extended MinProblemSolver::Function to 1) report the space dimensionality, 2) compute gradient if needed

refactored downhill simplex implementation a bit; hopefully, fixed the bug with random failures in the tests

Fixed getContinuousSize() to handle huge matrices properly. This should solve http://code.opencv.org/issues/3232