Add warning for untagged painted elements in multi haplotype assemblies.

[tommathers]

For multi haplotype assemblies it would be useful to add a warning / error message when there is a painted scaffold that does not have a HAP_(n) tag. This will avoid chromosomes being missing from the curated assembly when they have accidentally not been tagged.

[jgrg]

In general we need a clearer error message when there are departures from the expected pattern of tagging and ordering of chromosomes. I'm thinking of a tabular layout for the error message.