"DotBracket" seqtype missing from compatible seqtypes starting with 2.79.2

[FelixErnst]

Using the Stringstrings package as an example:

library(Structstrings)
data("dbs", package = "Structstrings")
file <- tempfile()
writeXStringSet(dbs,file)
# Error in compatible_seqtypes(from_seqtype, to_seqtype) : 
# seqtype1 %in% .SUPPORTED_SEQTYPES is not TRUE

I have mitigated the issue in Structstrings by adding the conversion to BString in the helper function writeDotBracketStringSet.
However, I think this might cause downstream issues, if the assumption is that writeXStringSet can write all XStringSet objects.

@hpages do you want "DotBracket" as an additional seqtype or do we continue with the mitigation in Structstrings?
("DotBracket" is in all regards a "B")

[FelixErnst]

I added the seqtype as PR.

Alternatively, the fix is in this branch add Structstrings and can be added any time to devel: https://github.com/FelixErnst/Structstrings/tree/Biostrings2.79.3