Add dynamic data to PointAnnotationOptions.

[fluttermoonger]

Would like to see the possibility to add custom data to the pointannotationoptions.
Let's say I have a custom class that I need to pass to the annotationclicklistener. Cant do much with variables that are their now

[m-ochyra]

I'm using textField property to pass ID of the item. I also set textSize to 0, to hide this value on the map.

[vanvixi]

I'm using textField property to pass ID of the item. I also set textSize to 0, to hide this value on the map.

This is just a trick for PointAnnotation, for Polygon is not possible.

[tomblixt]

I came for now to this same solution. Has any of you found a better way to do this? For example in iOS, you can add properties to the userInfo of an annotation. And in Android, you can add data with the withData function

[tomblixt]

#171 It looks like this PR adds this functionality