GNII Max Alt warning

As implemented in the latest version the maximum value of Max Altitude
is limited to 15,000ft which is not useful in SW USA. It should be
obvious to anyone that the limit should be setable at least as high as
18,000ft. In fact there is no reason for any hard limit at all as the
pilot may fly in a wave window.

Anyone using GNII at R9 Parowan should be sure to turn off this
warning. Not only is the warning useless it takes up screen area and
prevents access to the normal user interface until the glider descends
below 15,000 ft.

I nearly threw the damn thing out of the window while flying above
15,000 ft at Springerville, AZ last weekend.

Perhaps if enough users complain about this there just might be a new
release with a fix. I tried hard to get it changed several years ago
but was ignored.

Andy