added option for teacher forcing. Fixed SoftmaxCrossEntropyIgnoreIndices loss. Added test for Show, attend and tell architecture

Renamed load_data(batch_size, img_size) to load_data_img because it clashes with load_data(train_batch_size, test_batch_size)

Fixed a bug which occurred when an empty network (a network which contains only an assignment) was used

Removed inline mode, changed generation of execute and python execute and implemented beam search for both python and c++

Added possibility to save the visual attention for Show, attend and tell architecture as an image. Adjusted axis parameter in softmax layer to ignore batch size. Fixed a problem with some states not being initialized correctly in C++ code due to previous changes to the inline mode

Added BroadcastAdd and Multiply layer. Renamed Multiply layer to BroadcastMultiply. Added axis parameter to Softmax layer. Added SoftmaxCrossEntropyLossIgnoreIndices to SupervisedTrainer for now, in order to ignore certain words/indices for loss computation in NLP applications