v4.20.0 - Playtime variable, new helpful command & small improvements

[AlessioGr]

ATTENTION: VERSION 3 AND OLDER ARE NOT COMPATIBLE. ⇒ [Updating from <v4 guide](https://www.notquests.com/docs/documentation/updating-from-v3-or-older/).

• [+] New Variables: PlayerPlaytimeTicks, PlayerPlaytimeMinutes and PlayerPlaytimeHours
• [+] Added super helpful /qa variables check command
• [^] Improved startup messages for registering stuff
• [^] Updated dependencies
• [@] New translations
• [!] Make sure QuestPlayer exists before opening GUI

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This discussion was created from the release v4.20.0 - Playtime variable, new helpful command & small improvements.