Mapper code update

[yiids]

When changing code in a Mapper device, sometimes the code isnt properly applied, and one needs to press the stop button in order for the code to work. in the example of the screenshot, when moving the midi controller MIDI:/1/control/19, the midi value updates in the device explorer. If there is a syntax error in the code, it obviously will not change the value of the mapping correctly. But in the screenshot the syntax is corrected. However when you move the fader, you only see the midi value change, not the channel1 map. When you press stop, it does change.

[jcelerier]

ouch, actually you shouldn't be able to edit the code at all if the score is playing right now as it's unsafe