Changed EMBOSS version check to use new -otmopt flag for v6.5 or below.
Changed text to reflect the EMBOSS version check for v6.5+, for -otmopt flag

According to the docs at http://emboss.sourceforge.net/apps/release/6.5/emboss/apps/eprimer3.html
and http://emboss.sourceforge.net/apps/release/6.4/emboss/apps/eprimer3.html the relevant change
was between versions 6.4 and 6.5 - not 6.5 and 6.6 as I had thought.