nnForge v1.1.3

I labelled the latest changes in nnForge with v1.1.3:

• Snapshot functionality is redesigned fully - it is now doing backpropagation, the feature is still in beta
• Ability to define custom error functions is added
• Cross-entropy error function is added, use with care - not tested yet
• Galaxy Zoo example added - see Galaxy Zoo challenge
• cuda_max_global_memory_usage_ratio is set to 0.8 by default - This should help those running code on a primary videocard
• per_layer_mu mode is added - More robust training in some cases
• Fixes:
• Fixed crash when using output transformer
• Fixed backprop for local_contrast_subtractive_2d_updater in CUDA backend
• Fixed build with Boost 1.55