Dark-matter

Added `bin/add-support-to-iqtree2-issue-343.py` script for adding support
labels to nodes in trees produced by `iqtree2` when (if not run with
`-keep-ident`) it adds nodes and tips for identical sequences. `iqtree2`
currently does not put a support label on (the edge leading to) the tip in
the original processing or onto the nodes introduced by adding tips for the
identical sequences. This is described in the `iqtree2` GitHub [issue
343](https://github.com/iqtree/iqtree2/issues/343).

This was merged late and became version `5.0.19`.

Added `--rotate` and `--maxWindows` options to `window-split-alignment.py`.

Added `intsToRanges` and `intsToStringRanges` to `dark/utils.py`.

Added `bin/curate-trees.py` script to collapse low-support branches in
phylogenetic trees (to make polytomies) and also to re-root and ladderize
them.

Added typing hints to `dark/process.py`.