Ability to add attachments to messages#155

We have a fairly lengthy document which contains useful information for parents and carers about the practicialites and ethos of a day out in the woods with us. It involves a lot of scrolling on the eequ message facility. If it could be embedded as an attachment then people can open it more fully and it’s just a whole lot easier to read. It also would mean that newer, shorter messages wouldn’t run the risk of getting ‘lost’ in amongst the lengthy ones!