Add Pos.Align to ease aligning subviews: Left, Right, Center, Justify

[tig]

Pos/Dim work wonders for layout. However, aligning a set of controls (e.g. in the center) requires quite a bit of annoying code.

E.g. Dialog has this code to center buttons:

The new Wizard has fairly generic code for center, justify, right, and left alignment of buttons.

I would be easy to extract this code such that it would be easy to take a group of controls and horizontally align them.

The same thing could be done vertically.

e.g.

void LayoutStartedHandler ()
{
  View.AlignControls (Alignments.Justify, arrayOfControls);
}

[tig]

This will partially address this, by making right justification easier:

• Add Pos.AnchorEnd () (no param) to automatically account for the view's dimension #481

Related:

• Finish Dim.Auto - DimAutoStyle.Content is half-baked #2432