Allow aliases to also be specified in the 'default' section, but
    require that there must also be a 'species' setting in the same
    section.  Aliases will never be installed if there is no 'speices'
    setting in the current section.  The 'species' section may be
    inherited from the 'default' section.

    Example:

    [default]
    host    = db.example.com
    user    = anonymous
    species = Human
    alias   = H_Sapiens
    alias   = Homo_Sapiens
    alias   = Me

    [my_core_db]
    group   = core
    dbname  = homo_sapiens_core_45_36g

    [my_estgene_db]
    group   = estgene
    dbname  = homo_sapiens_estgene_29_35b