Taken a while to update to newer version.

First problem is I had to delete 5 plugins that were not compatible with something, so will make a post on that later.

Second Sort calendar plugin as usual
On front page only the calendar plugin errors occurred.
[/plugins/calendar.plugin.php]
Line 560 (both parameters obsolete
delete callspacing="0"
rename summary to title
Line 575
delete abbr="[abbr]"

Third On InSkin login page 2 errors
1. error: Bad value for attribute action on element form: Must be non-empty.
From line 161

See: https://github.com/b2evolution/b2evolution/commit/db86b08da74c93efeaea60b3fff5f888e9927a60

TODO
2. error: Attribute tag not allowed on element input at this point.
From line 156, column 55; to line 156, column 163

OLD Resolution
Unacceptable {tag} attribute inside {input} tag
file [/inc/core/ui/forms/_form.class.php]
Lines: 2935, 3694, 3698

change 'tag' to 'data-tag'
see http://help.simplytestable.com/errors/html-validation/attribute-x-not-allowed-on-element-y-at-this-point/