[ticket/16865] Update IRC + discord links in composer and documentation
Update the links from Freenode to Libera.chat,
add discord as option to chat in composer.json,
and remove references to wiki.phpbb.com
(And replace it with links to the development documentation)

PHPBB3-16865

[ticket/16865] Update IRC + discord links in composer and documentation
Update the links from Freenode to Libera.chat,
add discord as option to chat in composer.json,
and remove references to wiki.phpbb.com
(And replace it with links to the development documentation)

PHPBB3-16865

Merge pull request #203 from iMattPro/updates
Extension testing tutorial updates for 3.3.x

Merge pull request #202 from phpbb/ticket/201
Resolve incorrect formatting and invalid references

Merge pull request #200 from phpbb/ticket/199
Document use of rebase for updating branches

Merge pull request #195 from phpbb/hanakin-patch-4
fix link to languages page

Merge pull request #197 from phpbb/hanakin-patch-6
update irc and add discord to match .com

Merge pull request #198 from phpbb/hanakin-patch-7
fix coding guidelines tree links

Merge pull request #185 from mrgoldy/dev-docs-in-readme
Development docs in README

[ticket/16287] After installation an error is given over statistics submission
The phpBB.com website required specific fields to be available for the
statistics. This change switched over to a new statistics page on
www.phpbb.com that uses form fields instead, and that returns JSON as value.

PHPBB3-16287

[ticket/16043] Check if not null before getting anything from the container
This is only happening when there is basicly an error during
init of the container.

PHPBB3-16043