removed some double promotions that sneaked in, as well as replaced fabs() with float-only fabsf() version. trashed doubles from _atof(). Considering trashing that whole function for KEIL builds.

git-svn-id: https://afrodevices.googlecode.com/svn/trunk/baseflight@439 7c89a4a9-59b9-e629-4cfe-3a2d53b20e61