add simple interrupt handler class for optimzation process.
Fix example.
Refactor new logging function, use it for MNIST.
remove unused #include <set>.
Fix bug in visualization.
Merge branch 'master' of github.com:AlexanderFabisch/OpenANN
Merge branch 'interrupt' of https://github.com/Ruun/OpenANN into Ruun-interrupt
Refactor and test on MNIST.
Fix bug.
Fix renamed enum constant.
Merge branch 'master' of ssh://github.com/AlexanderFabisch/OpenANN

Conflicts:
	OpenANN/optimization/StoppingInterrupt.h
	src/StoppingInterrupt.cpp