Add ground station settings detail info for tooltips

[steveatinfincia]

v0.3.0 added tooltips for each ground station setting, the information for them comes from the settings model/mapping. Each setting in the mapping can include an optional field named "info". The text in that field will automatically show up in the tooltip, and if a setting doesn't have one then "N/A" is currently shown.

The only settings that have an info field at the moment are DISPLAY_OSD and ENABLE_QOPENHD.

The tooltip area can be increased if it proves to be too small for the information we need to display there.

[pilotnbr1]

Very nice! This makes the info block accessible to non coders

[pilotnbr1]

The info field can be found at-

https://github.com/infincia/QOpenHD/blob/master/qml/ui/SettingsMap.qml#L20

[pilotnbr1]

So if a tooltip does not have info I think it would be better to not display the "?"... Minor detail