initial pass at gpio cleanup. removed almost all dependency on stdperiphlib (remaining exti).
slightly modified initial pin configuration, but this needs rework soon anyway.
couple spacing/line ending/formatting fixes in sonar driver file while fixing gpio there.

git-svn-id: https://afrodevices.googlecode.com/svn/trunk/baseflight@357 7c89a4a9-59b9-e629-4cfe-3a2d53b20e61