GeoWidget: Enhancement - provide generalized mapping properties from data to tooltip fields for all layer types

**Build**

Detected in PR 365 - Dubsky fork

```
commit 361b63bc55ac4989f17f03f33165d3070c7236b2
```

**General Comment**

I've reported 3 issues regarding tooltips in GeoWidget and another 11 issues reported by others with the keyword 'tooltip' are open.

#403
#387
#293

**Enhancement Proposal**

Perhaps it would be better if there was a standard set of properties in the configuration for mapping data into tooltips.

_For example_

In one test case I'm using railway lines and would like to see the track number in the tooltip on the line and a station ID in a tooltip on an endpoint, along with other information, such as passenger count, speed, wagon count, parcel count, etc.

In another test case I'm looking at readings from gas meters as markers and marker clusters. I'd like to see an average last pressure calculation for all markers in the cluster along with a list of meter IDs when hovering the cluster and then the last pressure calculation and meter ID when hovering an individual marker.