Feature: PM Support

[tgxn]

What do you want to see? A way to view browse and respond to PM's.

Additional context As an admin, you end up messaging a bunch of people in regards to various things A page to view:

• [x] PMs received/sent PMs
• [x] Send new PM
• [x] #107
• [x] could have a notifications tooltip that just shows the unread ones....
• [ ] OPTION: auto-mark read on view (default: false)

[tgxn]

required for #90 and #46