Summary: Moved from GPL to LGPL with permission to link to other proprietary numerical libraries. Adjusted license notices in all files

Test Plan: unnecessary

Reviewers: pastewka

Reviewed By: pastewka

Subscribers: hu, MartinDoskar, jan.zeman4, rrezakha, gallyamov, afalsafi, maresca, RLeute, richart

Differential Revision: https://c4science.ch/D211