A warning more verbose, allow no alias, formatting

Other than some very minor formatting changes, the two changes here:
a) make a warning more verbose (I missed the meaning of the output)
b) allow the config file to have no alias value without causing an error.
Bio::EnsEMBL::Feature assumes it always has adaptor property, but sometimes
code (e.g. Ensembl web) creates features without an adaptor.
In case of circular slices, return seq_region_start|end from the db only if
an adaptor is available.
If there is no adaptor it will try to do the normal calculation rather than die.
ENSCORESW-941: only store an entry in the mapping_set table if there are two databases to compare
basic restore of original read_coverage code
Restore read_coverage support

Restore read_coverage data support removed in 75. Also support the has_coverage field and the downstream effects on rendered sequence of secondary strains - strains with no explicit read coverage data are represented in lowercase where there is no genotype call available.
Merge pull request #16 from dbolser-ebi/patch-2

A warning more verbose, allow no alias, formatting
Merge pull request #17 from willmclaren/master

Restore read coverage support
Merge pull request #18 from ens-ds23/master

Self-syntenies: construct MLSS correctly.
ENSCORESW-951: leave transcript display xrefs alone for LRGs
these are being set when importing the LRGs
ENSCORESW-952: ignore GOs which have been imported from Ensembl
we should not import our own annotation
ENSCORESW-936: do method can accept attr and bind_values parameters along with the usual statement
Update eukaryota.pm

Overwrite transcript_names_from_gene method for all Ensembl Genomes species so it doesn't add '-201' suffix to the gene names.
Update eukaryota.pm

Added method documentation to explains why they get overridden
Merge pull request #19 from arnaudxk/master

Update eukaryota.pm
table definition should use latin1 charset
if this is not the default for your mysql installation, characters will be bigger
this should have been 75, not 74
Header format column length fixed at 80 is too small for some GRCh38 seq_region names, forcing accession and version to span multiple lines.
ENSCORESW-955: typo in documentation
ENSCORESW-901: updated incomplete description
ENSCORESW-954: store the analysis if it has not been stored yet