Merge pull request #184 from cojennin/new-editorial-metadata-on-calendar

Edit editorial metadata (and other post data) on calendar
Use standard naming conventions for AJAX actions and methods

See #184
More naming standardization

See #184
Refactor! Clean up handle_ajax_update_metadata() for clarity, consistency, and security

Also, move $published_statuses to a class-level variable so we don't have to redeclare everywhere

See #184
Missed the class level variable

See #184
Merge pull request #187 from cojennin/multisite-usergroups

Don't allow display or update of user groups from network users page.
Fix typo for #184
Add a bit of underline when a calendar field is editable
Update readme for #187
Restore missing 'break'
Settings: Don't show any links to the feature if the module is disabled.

See #121
Resolve merge conflict
First pass at rendering the .ics feed. It includes some part of that, plus abstraction of filter validation and generation of each post's supplementary information.

It still needs:

* Proper validation that the request is acceptable.
* Feed should actually render in iCal.
* UI for the user to access their personalized feed.

For security purposes, the feed should include a key that's MD5 hash of the user's user_login and a secret key generated on activation and stored in options.
Generate a secret key we'll use to validate our hashes
Expose the user's ics subscription URL in screen options, and check the hash when rendering the subscription
Move the ics subscription handlers above the caps check. We want the subscriptions to be usable even when the user is ogged out
Add line folding and missing fields to pass ICS validation.
Merge pull request #171 from Automattic/ical

iCal subscription support for the calendar
Merge get_calendar_information_fields() into get_post_information_fields()
Update with props for #184