Images: move save modified images operator from Python to C

We will use this for saving images along with the .blend file.

Ref D4861

release/scripts/startup/bl_operators/image.py

@@ -115,39 +115,6 @@ class EditExternally(Operator):
         return {'FINISHED'}
 
 
-class SaveDirty(Operator):
-    """Save all modified textures"""
-    bl_idname = "image.save_dirty"
-    bl_label = "Save Dirty"
-    bl_options = {'REGISTER', 'UNDO'}
-
-    def execute(self, _context):
-        unique_paths = set()
-        for image in bpy.data.images:
-            if image.is_dirty:
-                if image.packed_file:
-                    if image.library:
-                        self.report({'WARNING'},
-                                    "Packed library image: %r from library %r"
-                                    " can't be re-packed" %
-                                    (image.name, image.library.filepath))
-                    else:
-                        image.pack()
-                else:
-                    filepath = bpy.path.abspath(image.filepath,
-                                                library=image.library)
-                    if "\\" not in filepath and "/" not in filepath:
-                        self.report({'WARNING'}, "Invalid path: " + filepath)
-                    elif filepath in unique_paths:
-                        self.report({'WARNING'},
-                                    "Path used by more than one image: %r" %
-                                    filepath)
-                    else:
-                        unique_paths.add(filepath)
-                        image.save()
-        return {'FINISHED'}
-
-
 class ProjectEdit(Operator):
     """Edit a snapshot of the view-port in an external image editor"""
     bl_idname = "image.project_edit"
@@ -248,5 +215,4 @@ classes = (
     EditExternally,
     ProjectApply,
     ProjectEdit,
-    SaveDirty,
 )