[ticket/8960] Allow changing avatar path if it's not writable

This change will allow users to change the avatar path even if it's not
writable. However, this will get rid of the error message that the path is
not writable. Due to this, a minor addition to the explain message in the ACP
settings has been made.

PHPBB3-8960
[ticket/12186] Move PM reports below post reports while installing

In mcp, move PM reports below post reports while installing.

PHPBB3-12186
Merge pull request #2319 from n-aleha/ticket/12186

[ticket/12186] Move PM reports below post reports while installing

* n-aleha/ticket/12186:
  [ticket/12186] Move PM reports below post reports while installing
Merge remote-tracking branch 'github-marc1706/ticket/8960-olympus' into develop-olympus

* github-marc1706/ticket/8960-olympus:
  [ticket/8960] Allow changing avatar path if it's not writable
[ticket/12467] Add config*.php and tests_config*.php to .gitignore

PHPBB3-12467
Merge pull request #2371 from nickvergessen/ticket/12467

[ticket/12467] Add config*.php and tests_config*.php to .gitignore

* nickvergessen/ticket/12467:
  [ticket/12467] Add config*.php and tests_config*.php to .gitignore
[ticket/12468] Having mbstring.http_input set to '' is as good as 'pass'.

PHPBB3-12468
Merge remote-tracking branch 'github-bantu/ticket/12468' into develop-olympus

* github-bantu/ticket/12468:
  [ticket/12468] Having mbstring.http_input set to '' is as good as 'pass'.
  [ticket/12467] Add config*.php and tests_config*.php to .gitignore