Avoid loading a plugin of the same name twice.
Avoid loading a plugin of the same name twice.

This should be the other half of fixing issues related to autoloading
plugins and plugin search paths, and should be resilient even to symlinks.

leemichaelRazer/OSVR-Core,OSVR/OSVR-Core,godbyk/OSVR-Core,OSVR/OSVR-Core,OSVR/OSVR-Core,godbyk/OSVR-Core,leemichaelRazer/OSVR-Core,OSVR/OSVR-Core,OSVR/OSVR-Core,OSVR/OSVR-Core,leemichaelRazer/OSVR-Core,godbyk/OSVR-Core,godbyk/OSVR-Core,leemichaelRazer/OSVR-Core,godbyk/OSVR-Core,leemichaelRazer/OSVR-Core,godbyk/OSVR-Core