Hide taxon specific gene accepting endpoints inside the non-taxon specific ones

[oganm]

The API includes 2 functions for most things accepting genes, one without taxon that will fail if an ambigious gene symbol is used and another with taxon that won't. Currently the packages do not include them but they do accept taxa that they pass as a filter. If a single taxon is given, it may be sensible to just use the taxon specific endpoint to avoid forcing users to specify gene ids.