Exit draw loop if `cTabActHcam` is not defined. Fixes #30.
When unloading Hcam GUI, call `cTabHcamDelCam` instead of `cTabUavDelCam`.
Unset `cTabActHcam` when closing Hcam GUI. Before we were drawing the position of an Hcam selected in a previous session, even when no Hcam was selected in the current session. Small tidy-up.
Some performance improvement of `cTabOndrawHCam`, less functions called.
Make sure we don't draw if `cTabActUav` is nil. Small performance tweaks due to less functions being called. Instead of drawing an icon for every UAV, only draw the icon and update the position for the UAV currently selected (we are only showing a small area, so the chance of seeing more than just the selected UAV is very slim).
Set `cTabActUav` nil upon unloading the UAV display. Stops UAV position of UAV selected in previous session even if the current session has no UAV selected. Small tweaks.