SpuriousSeedAnnihilator: disable debug messages by default

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
TaxonomyViewer: rename the plugin to TaxonomyViewer

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
remove plugin_ from all plugin directory names

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>