Add 'Filter Ratio' to tuning parameters

[ethomas997]

Adds 'Filter Ratio' as a new per-profile tuning parameter.

If the Profiles table in the current database does not have a filter-ratio column then the table is updated and the tuning profiles are reset to defaults.

--ET

[punkkills]

Do you use this parameter? I added this as an experimental value and found the default to work the best.

If you do use it, what values are you typically using and what situations does it help with?

If there is not a lot of value to the parameter, my preference would be to remove it rather than add to the already confusing set of tuning parameters.

[ethomas997]

@punkkills My thinking was to make it accessible to so it could be experimented with. :] So far I've found that at the maximum-filtering value (1) the displayed RSSI readings still seem quite responsive, so I was thinking of increasing divider factor (1000) in the node code to see what that does.

I'm wondering if a bit more filtering will decrease the chances of "false" lap-pass detections, especially in indoor FPV environments.

[ethomas997]

Yeah, I think increasing the divider in the 'filterRatioFloat' setups (in the node .ino) from 1000.0 to 10000.0 is worth doing. Even with that and "Filter Ratio" set to 1 the RSSI readings still seem fairly responsive. A "Filter Ratio" setting of 100 would match the current default, and 10 seems fine.

[ethomas997]

Rebased to master-20181112