tidy before doing more substantial work
identified a few errors, removed unused fields, etc
details below

basic.py
optimise imports
remove extra copy of member tensor_from_layer
fix clone method missing self argument

cost_layers.py
fix bad references in weight_noise initialisation
make get_cost & get_grads members match between cost layer and  linear layer
fix get cost argument name of additional_inputs misspelling and subsequent error of correctly named use elsewhere
remove unused variables

LM_Model.py
add comments for errors that need fixing; undefined variables for example
correct invalid reference to _cost that should be cost

SGD.py
fix mixed space/ tab issue in __init__
removed unused variables

SGD_adadelta.py
fix mixed space/ tab issue in __init__
removed unused variables

SGD_momentum.py
fix mixed space/ tab issue in __init__
removed unused variables