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.
Constraints
Add section that gives an overview of other libraries.
Put comparison in table.
OpenANN will be released under GPL.
Remove compiler switch USE_GPL_LICENSE.
Add convenience function train and remove train from Net.

Conflicts:

	src/Net.cpp
Extend Log interface for setting namespaces

Signed-off-by: Chris Mueller <christoph.mueller@dfki.de>