Option to give leaf nodes in polytomies a default order in Tree.ladderize.

[davipatti]

I added this option to reduce unnecessary cross overs in tangle plots of trees that have polytomies.

[mmore500]

@davipatti thank you for the contribution! I’m hoping to follow up and review it this upcoming week 👍

[mmore500]

@davipatti — do you think similar functionality could be achieved by sorting the tip polytomies before the ladderization process?

[davipatti]

@davipatti — do you think similar functionality could be achieved by sorting the tip polytomies before the ladderization process?

@mmore500 sorry for being slow to reply. I guess that could also work. This seemed like a more explicit approach.

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[mmore500]

@davipatti I ended up pushing to the wrong branch by accident, so this pull request ended up closing sooner than I intended without being able to run suggestions by.

I implemented a "reorder" function that, by default, sorts by label. I added a note to the documentation suggesting that ladderization sort is stable, so to control order within ladderization, call reorder before ladderizing. Let me know if this covers your use case.