[ticket/11700] Add develop scripts to use namespaces and rename interfaces

PHPBB3-11700
[ticket/11700] Move all recent code to namespaces

PHPBB3-11700
[ticket/11700] Namespaces and class names should not start with digits

PHPBB3-11700
[ticket/11700] Fix number class names in 3.0.x migrations

PHPBB3-11700
[ticket/11700] Fix avatar tests

PHPBB3-11700
[ticket/11700] Fix config db tests after namespace mishap

PHPBB3-11700
[ticket/11700] Fix dbal tests after config namespace mishap

PHPBB3-11700
[ticket/11700] Fix class loader tests for namespaces

PHPBB3-11700
[ticket/11700] Fix config namespace mishap in cache tests

PHPBB3-11700
[ticket/11700] Fix expected class name output from dbms convert

PHPBB3-11700
[ticket/11700] Correclty use namespaces in notifications

PHPBB3-11700
[ticket/11700] Use underscores for generated search test wrappers

PHPBB3-11700
[ticket/11700] Avoid \t in double quoted strings for template code

PHPBB3-11700
[ticket/11700] DI container test needs namespaces to work properly

PHPBB3-11700
[ticket/11700] Get the installer to run with namespaces

PHPBB3-11700
[ticket/11700] Don't prefix dbms classnames with \

PHPBB3-11700
[ticket/11700] Update finder tests for namespaced classnames

PHPBB3-11700