Last Opened Athlete stored

... last opened was not stored any more in 3.1 final build
Fix RideNavigator No Focus text color

.. was gray on gray which didn't work well !
Initialise Record count WKO+ file reader

.. don't accept an empty wko+ file.

Fixes #1064
Merge pull request #1065 from Joern-R/pull1

Last Opened Athlete stored
merge upstream into master