#257 Use 'replaced by' and 'consider' annotations

[Melissa Haendel]

For the obsolete terms, there is often information in the comments field about what other term to consider. It would be great if these were computable using the the 'replaced_by' and 'Consider' annotation properties.

In obo format, add to a stanza with an obsolete boolean:
consider: HP:0000490
OR
replaced_by: HP:0000490

URIs:
http://www.geneontology.org/formats/oboInOwl#consider
http://purl.obolibrary.org/obo/IAO_0100001 (labeled 'term replaced by')

[Peter N. Robinson]

I added consider/replaced-by as appropriate for all obsoleted terms.