Small updates and error catching

This new update adresses some issues linked to cellpose failing on large tiles, most likely linked to there being overly small tiles being created in some cases.

This was adressed for now by either ignoring images that are too small (which should be included in the overlap between tiles anyway) and by adding a check in case reading a label image has an error, which initially caused the extension to simply crash.

A new builder parameter setOutputModelName(String outputName) allows you to rename the resulting cellpose model after training.