v6.0.0

• Use a more compact cookie format
• Fix issue where a cookie key could have a space appear inside of it
• Allow for localStorage fallback with the disableCookie option.
• Only new and unseen devices will get the compact cookie. cookieForceUpgrade will force all browsers to upgrade and delete the old cookie.

Breaking Changes

• The cookie format has been changed to be more compact. If you use the same Amplitude project(API key) across multiple applications, and you track anonymous users across those applications, you will want to update amplitude across all those applications at the same time.