Add date-stamp in output.

In warning():
  Add date-stamp in output.
  Make subroutine argument parsing work as for throw().
  Output message using warn() instead of to STDERR with printf().

now uses 1G for human rather than more than 4G

Using the new -rc_name and setup 2 classes sized according to the process from a 67 run of the pipeline. Both have been given room to grow. We will see if it's enough during production

updated the $option in seq region stats snp case . seq region stats snp script now use "-pattern" to find a database instead of -d.

populate xref description with ensembl object description if the xref description is empty and copy_description_from_object parameter is true

VEGA haplotype slices are non-reference now:

1. add predicate for haplotype slices;
2. workaround for issue with API where haplotype slices are non-reference
    but have no assembly exceptions;
3. fix map_assembly.pl so that it doesn't assume non-reference is a patch.

The other half of this commit is in ensembl-otter git.