content_subtype was a parameter to message_post allowing to give plaintext
content instead of html content. It has been removed at 74d4b3902d. This
commit cleans some leftover bits referencing this now removed parameter.
content_subtype was a parameter to message_post allowing to give plaintext
content instead of html content. It has been removed at 74d4b3902d. This
commit cleans some leftover bits referencing this now removed parameter.