Altitude Filters

[Allocator]

- Altitude filter does not work correctly on initial startup.

- Set lower altitude filter to 10000ft and all aircraft except currently 'active' flight disappear

- Click 'Clear Filters' and all aircraft return and altitude slider stays at 10000ft

- No way to reactivate altitude filter without moving slider again

- Having cleared altitude filter using button, dragging slider to 0ft makes filter active again and only shows aircraft at 0ft.  Need to click 'Clear Filters' button again to restore aircraft.

- Leaving lower filter at 0ft and setting upper filter seems to work correctly throughout upper height filter range.

- Having used upper altitude filter, when you use the lower altitude filter again, it does work!

- In summary, open RadarBox25 website and log in.  Use lower altitude filter and it does not work correctly.  Use Upper filter (which does work correctly) then lower filter works correctly too.

- Bug is repeatable.

[AirNav 3D Development]

I will try to get the filters working by next week. I think I know where the bug is but it'll take a few days for me to get to it. Thanks for the detailed list of issues (it really does help a lot).