Improvements to the custom pose storage system

[ClaudiaMia]

• An indicator of how many slots you currently use from the maximum amount of slots you have.
• Improve the generic string importer: Add a way to import several presets at once, so that I can import several ones at the same time. That means that the importer does not look for one valid string, but looks if there are more afterwards and tries to add as many as possible.
• Maybe a button to delete all poses at once with an "are you sure" dialog, so that you can quickly switch whole pose playsets as needed for an RP scenario.