[PATCH v2 1/4] emacs: Helpers needed for the user to be able to choose the "From" address when composing a new message

This adds functions and variables needed for this feature to be implemented. Once it's done, the user will be able to use a prefix argument (e.g. pressing C-u m instead of m) and be able to select a From address. By default the list of names/addresses to be used during completion will be

[PATCH v2 1/4] emacs: Helpers needed for the user to be able to choose the From address when composing a new message

This adds functions and variables needed for this feature to be implemented. Once it's done, the user will be able to use a prefix argument (e.g. pressing C-u m instead of m) and be able to select a From address. By default the list of names/addresses to be used during completion will be