model has been renamed to mail.channel to prepare the slack modeling.
In future commits the mail.group model will be merged with the channel
model from im_chat. The first move is to rename mail.group into
mail.channel to have a model that will unite both features.
renamed to mail.channel.
At this point no model has been renamed; only files have been moved.
n mail, mail_group files have been renamed to mail_channel. The
website_mail_group addon has been renamed to website_mail_channel.
Some internal references have been updated (templates, linked files).
Thibault Delavallée