Add code and icons to TinyMCE so that people can add inclusions, and links to cards and external sites, via GUI.
One design question is whether to render those in edit mode with brackets or wysiwyg-style. Multiple edit modes?
Drag and drop a card into an edit box to add a link to it, hold down shift to make it an inclusion?
duplicate of build link and inclusion editors.
+discussed in support tickets
+relevant user stories