FRSKY & HowHigh module Resolution & Variometer

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What new feature/ability do you want?
First actualy unless i am wrong the ER9X attempt to use Meter value from the 
module and offer a conversion to feet if the user ask for it in the interface.
That sad because if you configure your HowHigh Module to send feet instead of 
meter you can alway convert in meter if you want with the ER9X and you gain x3 
of resolution (Around 33cm precision instead of Meter precision)
With 0.33 precision you can manage to use this value to program a Variometer 
Beep.

What is the expected output?
- Allow HowHigh module to send Feet and use computation on the TX only for feet 
to meter.
- Variometer with 3 state 
 1) Off (nothing)
 2) ON_UP (if actual feet value > previous  stored feet value+1) then High Audio Beep and store new value into  "stored feet value static variable"
 3) ON_UP_DOWN  same behavior as ON_UP + (if actual feet value < previous  stored feet value-1)then High Audio Beep (low frequency) and store new value into  "stored feet value static variable"
I propose +1 or -1 from previous value to trigger only when +66 cm or -66cm of 
the previous recorded altitude wich allow noise around +1 or -1 feet to be 
ignored.

Please provide any additional information below.

I have already program those behavior and the Variometer function is very nice 
and convincing ,the only trouble is that i have hardcode the Off ON_UP and 
ON_UP_DOWN function to the 3 positions flight mode button because i do not want 
to break the memory pattern of the model so to be able assign programaticaly  
those function would require to add data to the actual struct ModelData.

Original issue reported on code.google.com by vinceofd...@gmail.com on 31 May 2012 at 12:38

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The How High using feet should work correctly in feet, just select it in the 
telemetry menu as the altitude source.

Original comment by michael....@mypostoffice.co.uk on 18 Jul 2012 at 5:45