Execute the edit callback function in a thread. By executing it in a thread
we don't have to wait for longer validation procedures to finish to
continue updating the UI. This is most notable in the MoveGamePopUp
which is heavy on disk IO.
Because we cannot use special text formatting in a thread, the
indicator messages have been reworked while also becoming extensible.
A dictionary of extended reasons can be specified through the
`IndicatorLineEdit.extend_reasons()` method.
The dictionary has to follow the following format
```
python
{
MyIndicatorReasons.REASON: self.tr("Reason message")
MyIndicatorReasons.OTHER_REASON: self.tr("Other reason message")
}
```
In the above example `MyIndicatorReasons` is a subclass of `IndicatorReasons`
which should be specified as follows
```
python
MyIndicatorReasons(IndicatorReasons):
REASON = auto()
OTHER_REASON = auto()
```
