BaseParser: inserts into "synonym" now explicitly specify columns
BaseParser: inserts into "synonym" now explicitly specify columns

Part of the 2018 xref sprint has been devoted to making the xref
database schema a bit more self-constrained so that it could in
principle work with database engines other than MyISAM. One of the
changes made here has been the addition of an internal key column to the
table 'synonym'. Make sure inserts into that table do not get confused
by the possible presence of a new column.

Ensembl/ensembl,Ensembl/ensembl,james-monkeyshines/ensembl,james-monkeyshines/ensembl,james-monkeyshines/ensembl,Ensembl/ensembl,james-monkeyshines/ensembl,Ensembl/ensembl