libelas

From the discussion in !6 (merged) :

Now that you mention the license. I never checked libelas and it turns out, that it is licensed under GPL v3 or later (see comment on elas.cpp). Which means we have 3 Options.

1. Dropping libelas
2. Stop distribution of PeTrack binaries
3. Release PeTrack under GPL v3 i.e. open source PeTrack ( LPGL of Qt, modified LGPL of Qwt and 3-clause-BSD of OpenCV should all be compatible with GPL v3, so it is possible)

We need to decide what we will do.