Add a way to lock the scaling, rotation, translation and skew of any selected objects, nodes, images...

Object manipulation enhanced

I had this kinda weird idea, but I think it's really powerful: What if we could have some lock icons that would entirely lock the scale, rotation, translation... of objects and maybe other things like nodes...

What I mean by this is, for example, we could have a workflow like this:

* Create two rectangles
* Select them both
* Click again on them to get the rotation handles
* Then lock translation of objects
* Then try to rotate them, and they would rotate in place

... So, each rectangle would rotate in place, because translation is locked. Maybe we already have something like this implemented through "Paste size separately" for scaling each object separately in place.

So my version of that would be, "Lock object translation, then try to scale, and objects scale in place".

The same concept works for scaling, rotating, skewing and translating.

Some more examples with two rectangles selected:

1

* Lock rotation
* Rotate the objects, and only their origins would rotate,
  so they move, but don't change the way they are rotated.

2

* Lock scaling
* Scale the objects, and again, only their origins change,
  while they keep the same scale.

3

* Lock translation
* Change rotation, scale, skew or anything else of objects,
  while they stay in place, where they were before, all of them.

4

* Lock scaling
* Lock rotation
* Move, scale, rotate the selected objects, while they just
  change their positions, without scaling or rotating.

End

I think it would be kinda cool to have this implemented. It would allow for a lot of control over the objects, maybe even nodes, groups...

P.S. Making mockups for this would be a bit more time-consuming, but if there's a need, just let me know.