Scadnano

removed `forward` and `reverse` helper variables from scadnano. So you'll have to replace this:

python
import scadnano as sc

domain1 = sc.Domain(0, sc.forward, 0, 10)
domain2 = sc.Domain(0, sc.reverse, 0, 10)


with this

python
import scadnano as sc

domain1 = sc.Domain(0, True, 0, 10)
domain2 = sc.Domain(0, False, 0, 10)

Swapped role of `x` and `z` in `Helix.position` to match that of codenano.

`y` still has the same meaning: increasing moves down the main view and side view.

Increasing `x` now means go right in the main view, and go into the screen in the side view.

Increasing `z` now means go right in the side view, and go out of the screen in the main view.

Grid-based designs should still work simply by re-running the script using v0.9.0 or later of the Python library: https://github.com/UC-Davis-molecular-computing/scadnano-python-package/releases/tag/v0.9.0

However, Python scripts that set position manually in a gridless design using the old meanings of `x` and `z`, will need to be re-written to swap the roles of `x` and `z` in `Helix.position`.

Removed need to have xlwt installed if downloading the scadnano.py file and importing locally, unless an Excel file needs to be written.

Removed support for Helix.rotation and Helix.rotation_anchor.

Removed pitch, roll, and yaw from Helix.position, and made them top-level fields in Helix.

See https://github.com/UC-Davis-molecular-computing/scadnano/blob/master/README.md for description of current data model.