Alert Improvements by Xon 2.10.13

• For install, remove old XF1 grouped alerts to avoid errors about unknown templates

• php 7.4 compatibility update (Requires XF v2.1.3)

• Add "Display unread alerts above read alerts in pop-up" option
• Add per-user option to make viewing alerts pop-up skip marking it as read

• Fix link generation for report summary (likes/reactions/etc) alerts
• Fix your profile post comment like/reaction summaries link to the profile and not the profile post comment
• Fix profile post like/reaction summaries link to the profile and not the profile post

• Fix typo in phrase
• Fix XF2.1 summarization by user not listing reactions & summerized content types

• Fix typo in 'alert summarization' phrase

• Fix XF2.1 summarized/grouped alerts support

• Add missing phrase in XF2.1
• Load javascript required to make 'mark-unread' link work outside the alerts page.

• Remove use of get_lock which is unsupported in galera clustering, and causes errors in Percona XtraDB Cluster.

• Fix XF2.1 adding options to account preferences page