CanDo export

[UnHumbleBen]

The csv output format from scadnano is pretty close to that required by CanDo. The .csv from scadnano needs to include headings and colors of strands.

Related issue in web app

[dave-doty]

The export format seems to be closer to oxDNA (e.g., listing all nucleotides, and giving them positions) than the csv: https://cando-dna-origami.org/cndo-file-converter/

I think I'll start working on this, because it would be nice to use CanDo without having to go through cadnano as an intermediate.

[dave-doty]

TODO: Dave should implement the following:

• handle raise exception on unpaired insertions/deletions in Design.inline_insertions_deletions and oxDNA/oxView/CanDo export #227
• write method Design.domain_at_address and create an immutable Address class similar to the Dart code. The method will return a dict[Address, Domain] mapping each occupied Address in the Design to the Domain at that address. This can be used to calculate base pairs: if we have a base at an address, negate the forward field of the Address and look up the corresponding domain d in the dict; if there is one, then d.dna_sequence_in(offset, offset) is the base at that offset.

UPDATE: Dave implemented both of these in branch 167-cando-export..