J3.0 Administration: Fatal error in diagnostics page
Merge remote-tracking branch 'origin/master'

Conflicts:
	components/com_kunena/admin/template/joomla25/tools/diagnostics.php
Admin tools: Fix aliases during category recount
Fix #1745: Preview link doesn't have menu item
Fix #1760: No categories are shown on first visit
Merge pull request #1776 from mahagr/master

Fix #1745, #1760, fatal error in diagnostics & fix aliased during category recount