[feature/only-op-can-view] Missing TAB

On functions_display.php

PHPBB3-10623
[feature/only-op-can-view] Message in posts count forum list

As no one suggested anything better to use, I decided to make a message myself. The message that was there was just a placeholder until an appropriate message could be found.

PHPBB3-10623
[feature/only-op-can-view] Send logic solvable in php to php

After some time thinking, I was able to full implement as I understood that was requested by p (imkingdavid) which I failed to understand at the time.

PHPBB3-10623
[feature/only-op-can-view]  Decompiling the ternary operation

The ternary if, with the code I added, was not as easy to read and understand. With the purpose of following the same logic as the other 2 if situations, I moved the code to after the $read_other_forums condition and made it a complete if-then-else without using the ternary

PHPBB3-10623