2.8.4

Fixes

• Fix bug where experiment ID would be stale among paywalls sharing experiments
• Fix presentation_id changing mid-presentation when getPaywall() is called for a paywall that is already on screen. The id now rotates when a cached paywall is presented again, so every event between one paywall_open and the next carries the same id.
• Fix trial reminder notifications being scheduled after a paywall purchase that did not start a free trial (for example a user who already used their trial and was charged immediately). Reminders are now only scheduled when a trial actually started, and the paywall receives the freeTrial_start message for every started trial, even when it has no trial reminders configured.