Add "anchor" argument to scale method

[OpenFoam-User]

Similarly to the rotate method : rotate(angle, anchor, first) , the scale(factor, first) method should also accept an anchor.

Why:

Because if the scale is applied on the object multiple times, the object is moving and that's not necessarily the desired behaviour. So basically, scale should add anchor argument so the user could specify the center of the object to be used.

Steps to reproduce the reported bahaviour:

• Draw an object, e.g. a rectangle and select it.
• Run the following code:

  
  objs = svg_root.selection

for obj in objs: obj = inkex_object(obj) obj.scale(1.2)

When you keep pressing "Apply" button, the objects get scaled but move also.

![record](https://user-images.githubusercontent.com/67183566/149654781-f552701f-bf33-411a-b48b-95b55d5a71db.gif)

[spakin]

Similarly to the rotate method : rotate(angle, anchor, first) , the scale(factor, first) method should also accept an anchor.

That's a bit trickier than rotate because inkex doesn't support anchors for add_scale like it does for add_rotate, but I'll see what I can do…

[spakin]

Done. Please test.

[OpenFoam-User]

I have tested it and it seems to work perfectly! Many thanks

[OpenFoam-User]

Both rotate and scale don't work as expected for stars/polygons, text, and spirals: https://github.com/spakin/SimpInkScr/issues/35