repair or remove expfit-galaxi

Fit example expfit-galaxi currently generates very bad fits. This needs to be repaired; otherwise it would be better to remove the example.

On the road from v19 to v20, the distribution of particle radii was outcommented. This needs to be repaired first.

• Improve errmsg from importing sample
• By default, import function get_sample()
• Restore means to rotate detector