Adopt license management via Reuse project/tool (#711)

* reuse-managed license/copyright headers

reuse is a tool for compliance with the REUSE recommendations. See
<https://reuse.software/> for more information, and
<https://reuse.readthedocs.io/> for the online documentation.

* Set jsoncpp license
* Add MIT license for Decklink sources
* Explicitly license examples/
  - Add headers to source files
  - Change blanket licensing in .reuse/dep5 to only cover binary media
  - Import CC-BY-3.0 license and assign to sintel_trailer

examples/Example.py

@@ -9,26 +9,9 @@
  @ref License
 """
 
-# LICENSE
-#
 # Copyright (c) 2008-2019 OpenShot Studios, LLC
-# <http://www.openshotstudios.com/>. This file is part of
-# OpenShot Library (libopenshot), an open-source project dedicated to
-# delivering high quality video editing and animation solutions to the
-# world. For more information visit <http://www.openshot.org/>.
 #
-# OpenShot Library (libopenshot) is free software: you can redistribute it
-# and/or modify it under the terms of the GNU Lesser General Public License
-# as published by the Free Software Foundation, either version 3 of the
-# License, or (at your option) any later version.
-#
-# OpenShot Library (libopenshot) is distributed in the hope that it will be
-# useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-# GNU Lesser General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with OpenShot Library. If not, see <http://www.gnu.org/licenses/>.
+# SPDX-License-Identifier: LGPL-3.0-or-later
 
 # This can be run against an uninstalled build of libopenshot, just set the
 # environment variable PYTHONPATH to the location of the Python bindings.