Always name the imported action slot "Slot" when importing BVH and FBX files, for ease of switching between imported Actions. Note: this is only adjusting the old Python-based FBX importer. Previously the slot would be named after the file itself (BVH) or had a combination of the animated object, the animation "stack", and the animation "layer" (FBX). This meant that every imported animation would get another slot name, making Action switching tedious. Pull Request: https://projects.blender.org/blender/blender/pulls/146601