Calculation in instance properties

[jack-ii]

In Photoshop, Blender, etc., values ​​in fields for position, size, etc. can be added, divided, ...
This would also be very useful in GD, e.g. to quickly position object instances with the same distance.

I know a contributor tried this a few years ago, but the solution wasn't that good and it was canceled.
Since then we have AlexandreS & ClementPasteau on board and it might be worth another try :)

• Add value calculation for the properties panel (X, Y, W, H, Rotation)

[Bouh]

It was me with this PR, you'll have to start from a new PR, as my branch is outdated.
#2425