old_contents: import bpy
  from bpy_types import (Operator)
  from bpy_extras.io_utils import (ImportHelper, ExportHelper)
  from bpy.props import (StringProperty, BoolProperty, EnumProperty)
  from . import (importer, exporter)
  
  bl_info = {
      "name": "Clausewitz Import/Export",
      "category": "Import-Export",
      "author": "Bernhard Sirlinger",
      "version": (0, 3, 1),
      "blender": (2, 78, 0),
      "support": "TESTING",
      "wiki_url": "https://github.com/WebsiteDeveloper/ClausewitzBlenderPlugin/wiki",
      "tracker_url": "https://github.com/WebsiteDeveloper/ClausewitzBlenderPlugin/issues"
  }
  
  class ClausewitzExporter(Operator, ExportHelper):
      """Clausewitz Exporter"""
      bl_idname = "clausewitz.exporter"
      bl_label = "Export .mesh (Clausewitz Engine)"
  
      check_existing = BoolProperty(
          name="Check Existing",
          description="Check and warn on overwriting existing files",
          default=True,
          options={'HIDDEN'},
          )
  
      filename_ext = ".mesh"
  
      filter_glob = StringProperty(
          default="*.mesh",
          options={'HIDDEN'},
          maxlen=255,  # Max internal buffer length, longer would be clamped.
          )
  
      def execute(self, context):
          pdx = exporter.PdxFileExporter(self.filepath)
          pdx.export_mesh(bpy.context.active_object.name)
          return {'FINISHED'}
  
  class ClausewitzImporter(Operator, ImportHelper):
      """Clausewitz Importer"""
      bl_idname = "clausewitz.importer"
      bl_label = "Import .mesh (Clausewitz Engine)"
  
      filename_ext = ".mesh"
  
      filter_glob = StringProperty(
          default="*.mesh",
          options={'HIDDEN'},
          maxlen=255,  # Max internal buffer length, longer would be clamped.
          )
  
      def execute(self, context):
          pdx = importer.PdxFileImporter(self.filepath)
          pdx.import_mesh()
  
          return {'FINISHED'}      
  
  def menu_func_export(self, context):
      self.layout.operator(ClausewitzExporter.bl_idname, text="Export .mesh (Clausewitz Engine)")
  
  def menu_func_import(self, context):
      self.layout.operator(ClausewitzImporter.bl_idname, text="Import .mesh (Clausewitz Engine)")
  
  def register():
      bpy.utils.register_module(__name__)
      bpy.types.INFO_MT_file_export.append(menu_func_export)
      bpy.types.INFO_MT_file_import.append(menu_func_import)
  
  
  def unregister():
      bpy.utils.unregister_module(__name__)
      bpy.types.INFO_MT_file_export.remove(menu_func_export)
      bpy.types.INFO_MT_file_import.remove(menu_func_import)
  
new_contents: import bpy
  from bpy_types import (Operator)
  from bpy_extras.io_utils import (ImportHelper, ExportHelper)
  from bpy.props import (StringProperty, BoolProperty, EnumProperty)
  from . import (importer, exporter)
  
  bl_info = {
      "name": "Clausewitz Import/Export",
      "category": "Import-Export",
      "author": "Bernhard Sirlinger",
      "version": (0, 3, 3),
      "blender": (2, 78, 0),
      "support": "TESTING",
      "wiki_url": "https://github.com/WebsiteDeveloper/ClausewitzBlenderPlugin/wiki",
      "tracker_url": "https://github.com/WebsiteDeveloper/ClausewitzBlenderPlugin/issues"
  }
  
  class ClausewitzExporter(Operator, ExportHelper):
      """Clausewitz Exporter"""
      bl_idname = "clausewitz.exporter"
      bl_label = "Export .mesh (Clausewitz Engine)"
  
      check_existing = BoolProperty(
          name="Check Existing",
          description="Check and warn on overwriting existing files",
          default=True,
          options={'HIDDEN'},
          )
  
      filename_ext = ".mesh"
  
      filter_glob = StringProperty(
          default="*.mesh",
          options={'HIDDEN'},
          maxlen=255,  # Max internal buffer length, longer would be clamped.
          )
  
      def execute(self, context):
          pdx = exporter.PdxFileExporter(self.filepath)
          pdx.export_mesh(bpy.context.active_object.name)
          return {'FINISHED'}
  
  class ClausewitzImporter(Operator, ImportHelper):
      """Clausewitz Importer"""
      bl_idname = "clausewitz.importer"
      bl_label = "Import .mesh (Clausewitz Engine)"
  
      filename_ext = ".mesh"
  
      filter_glob = StringProperty(
          default="*.mesh",
          options={'HIDDEN'},
          maxlen=255,  # Max internal buffer length, longer would be clamped.
          )
  
      def execute(self, context):
          pdx = importer.PdxFileImporter(self.filepath)
          pdx.import_mesh()
  
          return {'FINISHED'}      
  
  def menu_func_export(self, context):
      self.layout.operator(ClausewitzExporter.bl_idname, text="Export .mesh (Clausewitz Engine)")
  
  def menu_func_import(self, context):
      self.layout.operator(ClausewitzImporter.bl_idname, text="Import .mesh (Clausewitz Engine)")
  
  def register():
      bpy.utils.register_module(__name__)
      bpy.types.INFO_MT_file_export.append(menu_func_export)
      bpy.types.INFO_MT_file_import.append(menu_func_import)
  
  
  def unregister():
      bpy.utils.unregister_module(__name__)
      bpy.types.INFO_MT_file_export.remove(menu_func_export)
      bpy.types.INFO_MT_file_import.remove(menu_func_import)
  
subject: Update Version