Redesign Edgenote creation/editing workflow

[cbothner]

• Don’t ask for an Edgenote slug—assign one randomly or just use id
• Provide a library of unattached Edgenotes to better facilitate moving them (this dropdown from the toolbar can also provide an easy way to “unattach” an Edgenote—that button changes to delete after it’s been unattached
• It’s really busy to look at the Edgenotes in editing mode—they should have a per-edgenote editing mode which exposes all the fields
• You know, other non YouTube embeds would be nice...

[cbothner]

#111