[WIP] Move flags declarations and warn user if unknown flags

Fix the output shape in python to match the C code for DownsampleFactorMaxGradGrad.

Correct In parameter name following Param removal

Fixes the multinomial grad dtype bug

Don't use CpuCorrMM when there is no CPU BLAS

change shape dimensions int32 to int64

Exponential Linear Units (ELUs)

Correct warning re: cuDNN and pool_2d's ignore_border argument

# The first commit's message is:

moving flags to configdefaults

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#	moving rest to configdefaults

Fix CudaNdarray repr in python 3 and a crash.

Sample multinomial with replacement

fix gh-4036. We need the shape and we don't compute it. It wasn't timmed, so don't try this optimization.