v1.5.0 beta

The 1.5 branch will move to support PHP 7.4 and PHP 8.0, alongside support for MySQL 8. We also did some housekeeping by removing rarely-used external parts such as the OpenID login or the outdated TinyMCE integration.

What's Changed

• Prepare the documentation for 1.5.0 by @fiammybe in #1215
• Updated branch references & readme by @MekDrop in #1223
• Remove TinyMCE by @fiammybe in #1273
• Remove openid by @fiammybe in #1274
• align syntax of DB interface and mysql implementation with PDO by @fiammybe in #1287
• prepare for 1.5.0 beta by @fiammybe in #1286
• Fix mailuser by @fiammybe in #1288

Full Changelog: v1.4.4...v1.5.0-beta