Billing for Multisite networks
- fixed Billing tab link in Edit Site (Network Admin) interface
- adding basic Billing setting page for child sites under
/wp-admin/index.php?page=billing - standardized billing plan labels for consistency
- improved security with sanitization, nonces, escapes, etc.
- better handling of site IDs
- various code cleanup
- added disable wordpress.org snippet
- added VIP level
- support for Git Updater
- Free, Basic, Premium levels
- payments not supported yet (hopefully soon)