learning circles

coordinate study groups for online courses

Revert updates to learner messages so we can release scheduling updates without breaking translations

Add character count input, rename template, generate meetings using dates rather than old meeting generation code

Reword reminders to generate full html message that can be edit by facilitator. Correctly handle different scenarios when editing meetings

Update copy for reminders and rework logic to allow HTML in messages. Also allow facilitator to edit entire message, while ensuring the unsubscribe link is still there