Update code and tests for short multi-line tooltips

Global changes of "<br>" to "<br/>" for JAL-3468 didn't extend to method JvSwingUtils.wrapTooltip() or its unit tests. As a result, this method no longer recognises 'multiline' tooltips, which should be left unstyled if all lines are less than 60 characters long.
For example, with uniref50.fa and exampleFeatures.txt, FER1_MAIZE column 60, the tooltip is wider (with blank space) in develop than it is in 2.11.