Change task Requiered Altitude Calculation :
if next Tp Requiered Altitude is less than current tp altitude, use current tp altitude for requiered altitude...
 - AAT Task : altitude of AAT Target point is used if upper center altitude, otherwise, center altitude is used.
 - PG optimized : always use Optimized point altitude. (reverted from commit 14c9a655a322867ee7f8643a1548078100dc22e4)
Fix Glide Bar should not be visible when there is no valid start, if it is configured to show task arrival altitude.
Beside, the value shown without a valid start was wrong.
Add support for the chinese bluetooth keyboards.
This is the first layout manager, BTK1.
The keyboard should be kept vertically with the space key on the right.
There is no need to look at it for using LK: simply think to be clicking on a screen:
think of the keyboard like it was a touchscreen.
The only special key is the corner SHIFT which is used as <enter> to confirm a goto.
To advance to next pages such as in landables, turnpoints etc, use the top screen keys.