Allow to specify the output message instead of always outputting to msg.payload

[janvda]

The output is always returned in msg.payload.
So it is overwriting the contents of the msg.payload.

To overcome this I have to surround the turf node by 2 change nodes:

• one to copy msg.payload in another variable
• one to copy it back to msg.payload.

So it would be good if I could also specify the output parameter name in the turf node configuration window similarly as you can specify the (input) Arguments.

For me there is no need to support flow and global output variables, msg is sufficient.
Eg. msg.country.shape