[ticket/12286] Use UTF8 (c) in style.cfg samples

PHPBB3-12286
[ticket/12286] Styles have a phpbb_version and a style_version in 3.1

PHPBB3-12286
[ticket/12286] style.php and imagesets dont exist anymore

PHPBB3-12286
[ticket/12286] Add "Since" to template event docs

PHPBB3-12286
[ticket/12286] Function names should be prefixed with phpbb_

PHPBB3-12286
[ticket/12286] Use $request->variable() instead of request_var()

PHPBB3-12286
[ticket/12286] Remove section about utf8_normalize_nfc()

The request class takes care of this

PHPBB3-12286
[ticket/12286] Classes must use the name space

PHPBB3-12286
[ticket/12286] Add section about plurals to the coding guidelines

PHPBB3-12286
[ticket/12286] Add note that goto should not be used

PHPBB3-12286
[ticket/12286] Fix nesting of ul inside li element

PHPBB3-12286
[ticket/12286] Correctly capitalize PHP

PHPBB3-12286
[ticket/12286] Fix spelling of elephant(s) in the sample

PHPBB3-12286
[ticket/12286] Reword section about plurals

PHPBB3-12286
[ticket/12331] Fix SQL error when inserting a new entry to profile field data

There was a "Field 'pf_phpbb_interests' doesn't have a default value" error,
because we didn't specify values for the disabled fields.
We can not disable the sql_return_on_error() thou, because it otherwise we run
into "Duplicate entry '2' for key 'PRIMARY'" errors when the user submits the
form again but didn't change any values.

PHPBB3-12331
[ticket/12282] Add Interface for DBAL drivers

PHPBB3-12282
[ticket/12282] Use {@inheritDoc} for inherited methods

PHPBB3-12282
[ticket/12282] Use interface for type hinting

PHPBB3-12282
[ticket/12282] Add new line at EOF of the interface

PHPBB3-12282
[ticket/12282] Update container db mock

PHPBB3-12282