Compatibility PHP 8 and Piwigo 15 (instead of sending the credentials by email, send an activation link for each created user)

New languages:
* עברית [IL]
* Íslenska [IS]
* Slovenščina [SL]

Compatibility Piwigo 12

New languages:
* Norwegian (Norsk bokmål [NO]), thanks to paulen
* Vietnamese (Việt [VN]), thanks to thanhphan467

Compatible with Piwigo 2.7

Use simplified function register_user from Piwigo 2.6

New languages:
* Catalan (Català [CA]), thanks to AlbertParera
* Esperanto (Esperanto [EO]), thanks to sylvbarrier
* Estonian (Estonian [EE]), thanks to Eggy
* Persian (فارسی [IR]), thanks to ipic
* Swedish (Svenska [SE]), thanks to kabo
* Ukrainian (Українська [UA]), thanks to marchelly
* Hong-Kong (中文 (香港) [HK]), thanks to hkdigit
* Traditional Chinese (中文 (繁體) [TW]), thanks to azq1231

New translations: Bulgarian (Български), Czech (Česky), Dutch (Nederlands), Portuguese Brazil (Português Brasil), Portuguese (Português)

Checked compatibility with Piwigo 2.5

New feature: ability to force usernames (see example)

New translations: Danish (Dansk), German (Deutsch), Greek (Ελληνικά), Spanish (Español), Hungarian (Magyar), Italian (Italiano), Latvian (Latviešu), Polish (Polski), Russian (Русский), Slovak (Slovensky), Turkish (Türkçe), Chinese (简体中文)

First version