- Better handling of radio/checkbox fields
- Added "provider" as a field type
- Added $can_add as an option to post types; set to false to disable the "Add New" menu item
- Added custom authentication for user profiles
- Added `skt_get_profile` which returns an array of user profile data
- Added `SKT_USERNAME_AUTH` constant to enable registration and login via email address rather than username
- Added payment module with a base payment provider class. Extend it to provide a payment mechanism (currently just handles a subscription model)