* Replace --input-h5ad-file with a positional argument, for consistency with other CLI commands
* Replace --update-h5ad-file with --overwrite, for consistency with `prepare` command.
* Fix/clarify various help descriptions
* Fix final output message when input file is overwritten
* Fix annotate top-level help description
* Fix float16 support [#2379]
Convert to float32 on startup unless backed, in which case error. scipy does not support complex slicing from float16 data so this is the easiest fix for now.
* minor msg change