Garmin Edge305 Firmware Update 2.80

Changes made from version 2.70 to 2.80:

* Improve accuracy of vertical speed and grade.
* Add feature to preview course map and course profile.
* Allow user to select course specific fields on the top half of the course timer page.
* Fix problem where today's scheduled workouts would not display if the local date was different than the UTC date.
* Fix problem where track log would not display in history if the timer was started without a GPS fix.