* split: ensure messagestore is available
* compose: only add signature if missing
* compose: allow changing edit-headers on the fly
* compose: implement embedded headers in editor
* compose: always use cr-lf line endings
* compose: improve error handling
* compose: factorize body read in a method
* compose: only allow setting content at creation
* send: return error when recipients list is empty
* imap: fix header cache key collisions
- Switch to the devel branch of my fork https://git.sr.ht/~mcepl/aerc
