Clarify licensing

[mdempsky]

In the top-level directory there's a LICENSE file that suggests the code is GPLv3, but then the "receiver" and "sender" subdirectories have their own LICENSE.txt files with a copy of the 3-clause BSD license. The inherited UDT code all reiterates the 3-clause licensing, but the newly added code is ambiguous whether you intend for it to be GPLv3 or BSD. (I'd encourage you to use BSD for consistency with UDT, but that's ultimately your decision.)

Could you please add copyright and licensing notices to the remaining files? E.g., sender/app/cc.h, sender/app/incast_client.cpp, and so on.

[millerabel]

With the publication of your article in Communications of the ACM, we have an interest in your work and would like to experiment in our Mojaloop.io project. However, we also would like to ask for clarity on the licensing. We would humbly request the BSD license to harmonize the included components and the project itself. Our intended use would be under our project’s Apache 2.0 license. (GPL is not compatible with Apache.)