implement untested neuron network
implementation of external managed memory
debug: typo
debug: typo, end of namespace
debug: public constructor
debug: implement sigma
Merge branch 'master' into dev/nn
include cstring
add standalone test program for nn
include stdexcept
Merge branch 'master' into dev/nn

Conflicts:
	test/Makefile
add test of neuronnetwork
correct gradient
[DEBUG] typo of initialization of n
debug: wrong ln
add CHANGELOG