#134: Introduce insert-license hook and fixup license headers

• Change license header's comments from docstring to #
• Introduce insert-license pre-commit-hook
• Get rid of update_copyright_year.sh which becomes useless
• Document how to update the copyright year

Close #134 (closed).

duniterpy/api/bma/__init__.py

-"""
-Copyright  2014-2021 Vincent Texier <vit@free.fr>
-
-DuniterPy is free software: you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation, either version 3 of the License, or
-(at your option) any later version.
-
-DuniterPy 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 General Public License for more details.
-
-You should have received a copy of the GNU General Public License
-along with this program.  If not, see <http://www.gnu.org/licenses/>.
-"""
+# Copyright  2014-2021 Vincent Texier <vit@free.fr>
+#
+# DuniterPy is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# DuniterPy 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import logging
 from . import network, blockchain, tx, wot, node, ud, ws