Option to add inline images in messages via the API.

When creating a message, it would be great to have an option to add inline images in the messages.

Maybe an extra parameter (hash map) which can be given to the create message request. This map would have a structure like {CID1: BASE64_ENCODED_IMAGE1, CID2: BASE64_ENCODED_IMAGE2, ... }. Then the CIDs can be referred in the HTML body to show the inline images.