Cleanup: remove redundant, invalid info from headers

BF-admins agree to remove header information that isn't useful,
to reduce noise.

- BEGIN/END license blocks

  Developers should add non license comments as separate comment blocks.
  No need for separator text.

- Contributors

  This is often invalid, outdated or misleading
  especially when splitting files.

  It's more useful to git-blame to find out who has developed the code.

See P901 for script to perform these edits.

source/blender/python/mathutils/mathutils_Vector.c

@@ -1,6 +1,4 @@
 /*
- * ***** BEGIN GPL LICENSE BLOCK *****
- *
  * This program 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 2
@@ -14,10 +12,6 @@
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- * Contributor(s): Willian P. Germano, Joseph Gilbert, Ken Hughes, Alex Fraser, Campbell Barton
- *
- * ***** END GPL LICENSE BLOCK *****
  */
 
 /** \file blender/python/mathutils/mathutils_Vector.c
@@ -2338,8 +2332,6 @@ static PyObject *Vector_length_squared_get(VectorObject *self, void *UNUSED(clos
  *                                 (axis_0_pos, axis_1_pos, axis_2_pos, axis_3_pos))
  *
  *     axises = axises[:-1]
- *
- *
  * items = list(axis_dict.items())
  * items.sort(key=lambda a: a[0].replace('x', '0').replace('y', '1').replace('z', '2').replace('w', '3'))
  *