New feature allowing for "new conversations"

The support guys have found Front to be really useful. I think if we had the facility to add a "new conversation" (just that without a lead or a problem) and then convert a conversation to a lead or problem (moving the conversation to then be a child of the problem/lead) then we would have the basis for similar functionality.

We could create a conversation from a new email, reply to it, establish what's what and if necessary turn it into a lead/problem.

Conversations could be a data type like lead/problem but much simpler, and fitting into the hierarchy in the same way (and so appearing in our "recent conversation/consolidated notepad" in a sensible way).

see also #PS365-I-2313