Some logging tidy-up

[dagewa]

logger.warning is used in a few places in the codebase. Use is not very consistent:

• logger.warning("*** WARNING: no reflections in job %d ***", index)
• logger.warning("Restraints will be ignored for scan_varying=True")
• logger.warning("Warning: Experiment crystals differ. Using first experiment crystal for file-level data.")

There are also warnings that aren't warnings

• logger.info("Warning: %d reference spots were not matched to predictions" % (len(unmatched)))

• It would be nice to have a consistent style. If logger.warning took care of the *** WARNING/Warning: or whatever prefix, this would help.

• Capitalisation - Warning: experiment not Warning: Experiment preferred

• Finally,

logger.info("\n")
logger.info("thing")
logger.info("\n")

one call per message please

[dagewa]

@Anthchirp I'm wondering how adding a prefix like "WARNING:" to logger.warning messages would work. Is it something that can be added to dials.util.log.config?