protect tester calls with pcall.
New NN classes
extra/nn/L1Cost.lua                       : L1 penalty
extra/nn/SpatialFullConvolution.lua       : full convolution
extra/nn/SpatialFullConvolutionMap.lua    : full convolution with connection table
extra/nn/TanhShrink.lua                   : shrinkage with x-tanh(x)
extra/nn/WeightedMSECriterion.lua         : mean squared error with weighting mask on the target

Add new nn classes that are used commonly for unsupervised training of convolutional auto encoders