Sort out years for licence so that they don't need to be updated in future.

LICENSE.rst

io_scene_nif/__init__.py

io_scene_nif/io/__init__.py

io_scene_nif/io/egm.py

io_scene_nif/io/kf.py

io_scene_nif/kf_import.py

io_scene_nif/modules/animation/__init__.py

io_scene_nif/modules/animation/animation_export.py

io_scene_nif/modules/animation/animation_import.py

io_scene_nif/modules/armature/__init__.py

io_scene_nif/modules/armature/armature_export.py

io_scene_nif/modules/armature/armature_import.py

io_scene_nif/modules/collision/__init__.py

io_scene_nif/modules/collision/collision_export.py

io_scene_nif/modules/collision/collision_import.py

io_scene_nif/modules/constraint/__init__.py

io_scene_nif/modules/constraint/constraint_export.py

io_scene_nif/modules/constraint/constraint_import.py

io_scene_nif/modules/geometry/__init__.py

io_scene_nif/modules/geometry/mesh/__init__.py