Verbose mode

[dorian3d]

Just a small enhancement: I think it would be good to have an option to enable/disable the verbosity of the library, or to set the stream the info messages are written to, so that std::cout is free for the application messages.

[floe]

I think this has been included by now, closing.

[christiankerl]

actually not ;) this is still a problem

[xlz]

This is implemented in #364. To be merged soon