Add hidden UI for mass-protecting content, refs #67
Allow plugin to disconnect from Memberful
Add helpers for generating the admin URLs
Add menu tabs to the plugin's settings page, refs #67
Add styling for global restrict access. #67.
Improve styling be separating the required for access and marketing content. Also moved to a <select> for the global options. #67.
Move admin settings from src/options.php into src/admin.php
Rework styling for the Bulk restrict access tool. #67.
Notify Memberful when home/blogname options change refs #82
Add basic API error logging to plugin #82

WordPress doesn't seem to have a built in transport for error logs, and
it's often hard for us to pinpoint the problems that are causing users
trouble as WP can just fail silently.

This commit introduces a basic error log that can be used for recording
failures from the Memberful HTTP API. Hopefully we can expand it to log
other Memberful related errors, and have the plugin auto-report them to
Memberful.
Fix typo in comment
Fix bug in debug view
Minor tweaks to the error logging in the api helpers #82

* WordPress downcases the headers returned by API calls
Use the correct nonce when disconnecting from Memberful.
Always send site settings when connecting to Memberful #82
Send site setting parameters in nested format, refs #82
Make sure users actually exist if they're in the mapping table #80
Allow authors to delete the current marketing content, refs #79
Allow authors to see the content of shortcodes without purchasing plan

fixes #83
Allow plugins to override the links in the profile widget, fixes #76