Adjusted vector sum kernel so that it can scale.
Adjusted computation of output local gradients so it can scale.
Adjusted parallel computation of total derivatives so it can scale.
Adjusted parallel computing of bias derivative so it can scale.
Adjusted computing of local gradient in hidden layers so it can scale.
Replaced custom clearLayer function with simple cudaMemset.
Eliminated duplicate function for computing vector sum.
Adjusted parallel computation of sigmoid so it can scale.