Distance Alert : Altitude Alert : Distance Slider - issue #191

[oam7575]

This pull request is from my second dev tree that has implemented

• Distance Filter : As per #249
• Distance Alert Beep - new
• Altitude Alert Beep - new

Distance and Altitude beeps are called during the table redraw as it allows for other filters to be in place to include / exclude air craft from the alert check.

The beeps are a slightly different Hz tone and are deliberately annoying.

Clearing the alert filter value, resetting the alert filter or excluding aircraft via the Altitude, Speed or Distance slider bar will silence the alert beeps.

To change the alert beep tone or "signal length" : check the scripts.js file between line 2400~2500 and change the values as desired.

[eric1tran]

Thanks! We'll give this a review and discuss whether we want to pull it in