Remove read coverage support

* dev:
  ensembl_ontology updated to release 75
  added new methods for readthrough counts more test cases for thoses
  test databases in sync with latest schema
  removed Test::Warnings dependency not available with default installation will come back under another form
  looking for value 94, not 58

more test cases for thoses

[ENSCORESW-797]. Use git show to retrieve whatever branch version of sql/table.sql file is requested.

not available with default installation
will come back under another form

fail. This fixes it by sorting out the auto increment identifier

Due to changes in BaseFeatureAdaptor we need to save the state of
meta_coord otherwise a number of tests will begin to fail. Same is
true of xref.

* dev:
  update attrib_type table, using longer varchar for 'code' column

if attribute already exists, not need to scream warnings

The read_coverage table and its API support are being removed
from the variation API; remove calls to these API components
and remove references from code docs

* dev:
  no need leaving unliked entries when removing slice, remove any attached assembly entries

when removing slice, remove any attached assembly entries

if this is the last feature of its kind, delete corresponding meta_coord entry
if it was the longest feature of its kind, update meta_coord to second longest feature

Thanks to Nathan and Gareth for pointing this out. Due to the Git migration
we now have to use ensembl-funcgen for the regulation checkout.

* dev:
  added option $filename for get_FTP if filename is specified, will save source to file rather than in an array good for big downloads

if filename is specified, will save source to file rather than in an array
good for big downloads