Improve orthogonalization action

[bhousel]

This PR fixes several long-standing issues with the orthogonalization action.

• closes Odd behaviour: square-an-area moves connected way #1979 - don't move connected way
• closes Squaring-Error #2472 - improve algorithm to handle edge cases
• closes Perfect squares cannot be squared as they are not squarish #5967 - don't show "not a square" error message for perfect squares
• closes Orthogonalizing paths #5093 - allow squaring of paths/lines
• Add square angles action on nodes #2205 ? - allow squaring a single edge when selecting a vertex
• add tests for the new vector math functions
• maybe use them in some other actions (straighten, etc) (will do after Straighten multiple ways in one operation #5740)

[bhousel]

So.. actionOrthogonalize can square lines now! which is #5093

However.. We already use the S keyboard shortcut for straightening lines, so it's kind of a problem having 2 menu commands with the same shortcut.

[quincylvania]

We already use the S keyboard shortcut for straightening lines, so it's kind of a problem having 2 menu commands with the same shortcut.

Could we intelligently choose square instead of straighten for lines when the line "can't be straightened because it bends too much?" I guess there are some instances where both are allowed though, and more importantly the user may mean to do one and get the other. I suggest switching the square shortcut to Q.

[bhousel]

I suggest switching the square shortcut to Q.

Yeah that would neatly solve the problem, and it's what JOSM uses too .. I'll do it.

[bhousel]

I guess there are some instances where both are allowed though, and more importantly the user may mean to do one and get the other.

Yeah it's actually really easy to construct a line that can be either squared or straightened... It's nice to have both options now!

[bhousel]

I added squaring a single vertex for #2205... It doesn't seem as useful as I thought it would be - just squaring one vertex in isolation of all the other ones - but maybe people will want it.

[bhousel]

I'm going to merge this.. The test failures seem related to #6001 / #6002 🤔