Remove unused dependencies & code cleanup

[kasimi]

Sorry, this has gotten a little out of control. 😇

While removing some unused dependencies from the services.yml and adjusting the constructors, I started going through the whole classes and fixed the formatting and other minor inconsistency. So, apart from syntax changes (which, again, cause these GitHub diffs to be extremely bloated), I fixed the following issues:

1. SEVERE: Fixed unauthorized access and XSRF vulnerability when adding messages
2. When unauthorized access is detected, the non-existing language variable MCHAT_ERROR_FORBIDDEN was used. Changed to MCHAT_NOACCESS
3. Fixed bug where the custom chat page displayed who is chatting when mChat is disabled
4. Using event core.display_custom_bbcodes_modify_sql to filter forbidden BBCodes and removed copy-pasted code from functions_mchat.php
5. Switched from deprecated get_user_avatar() to phpbb_get_user_avatar()
6. Save an SQL query when receiving an edit request from a user with moderator permissions

[dmzx]

Wow thanks again for your time!

[kasimi]

My pleasure. What about this one failed check? I'm not familiar with Travis and I don't understand what the Travis build log is telling me.

[kasimi]

Oh, you merged it already. Never mind. 😇

[dmzx]

A no problem just solved it's ok now