Feature-request: add SimpleDataField.setLabel()

Currently DF developers have 2 options when they want to be able to dynamically display some info in the DF (for example use some string that is based on settings)

1. Use SimpleDataField => no way to change the label => have to return it in compute => it makes the font of the field value alhanumeric => smaller font size => hard to read

2. Use DataField => need to "rewrite" all the following functionality of SimpleDataField:
 - which label font to use
 - where to position the label (aka justification + y position)
 - divider line
 - decide if (bigger) numeric font can be used to display the data or only alphanumeric font ("1.0" vs "1.0 km")
 - calculate the position of the data text (aka justification + y position)
 - calculate the biggest font that fits the value into the dimensions of the field (- label)
 - for all the above: take into account 11 possible obscurityFlag values
=> complex, high risk of bugs, leaves less free code memory for real features, will probably look different from built-in datafields

It will not be less than 500 lines of code and almost 10kb of code after compiled.