Fix group matching SQL query

The check there is intended for the :members_mods_and_admins level, which is not automatically checked for normal users. Instead, the :everyone level is the one used, which would always fulfill the "alias_level in :levels" check.

This changes the :everyone level to :members_mods_and_admins, which was originally intended.
Change to case-insensitive matching in group @name matching
Updated with tips for Postgres93.app

It took me a while to figure this out, so hopefully it helps someone use discourse in the future.
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Fix sanitization of smileys like <_< and <3.
Merge pull request #1866 from shivpkumar/master

make search on 404 page secure
Track how many posts a user reads each day in user_visits
Refactors Discourse.SearchController to use var self = this; convention
BUGFIX: make sure author's avatar is 45x45
BUGFIX: limit the height of code blocks to 500px
FIX: 1868 Security: Dangerous Send
Merge pull request #1875 from velesin/search_controller_context_binding_fix

Refactors Discourse.SearchController to use var self = this; convention
Show unread and new counts on sub-categories on /categories page
FIX: Missing module name
Add parent category link to title of topics in a subcategory
FIX: Scroll to top on categories view, too.
Merge pull request #1858 from shicholas/patch-1

Updated with tips for Postgres93.app
Merge pull request #1863 from ecuk/analytics

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Merge pull request #1865 from vikhyat/less-than-sanitization

Fix sanitization of smileys like <_< and <3.
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