First version of the Spoken Language Detection problem.

+ Added small tweak in application of gradients to force big gradients.
+ Hard coded softmax function in cnnbp and cnnff. TODO: make it
configurable.
+ Now you can configure a network with non squared input images(xscale
and yscale are separate).
+ cnntrain will now report the "errorSoFar" variable to follow the
improvements in your coefficients.
+ new function convn_valid to replace the missing convn().
+ Mean normalization and max normalization for MFCCs and input signals
respectively.
+ Under \data there's a bash script to convert from .flac to wav.