Combine masking logger calls

[rjgildea]

• Combine up to six consecutive logger.info() calls into a single call
• Change to debug-level log messages

[graeme-winter]

👍

graylog2 also says thank you

[rjgildea]

Tested with:

$ dials.generate_mask $(dials.data get -q centroid_test_data)/*0001.cbf d_min=2 d_max=10 resolution_range=4,4.5 untrusted.rectangle=100,200,100,200 untrusted.circle=100,100,10 border=10 polygon=100,100,100,200,200,200,200,100 ice_rings=True -vv

[ndevenish]

I've argued myself in circles over whether the concatenation makes sense so am going agnostic