[ticket/12662] Change new event names and fix events.md

Previously merged PR said b4 instead of b5, also not alphabetical.

PHPBB3-12662
[ticket/12662] Use slack variable to determine line-break sensitivity

PHPBB3-12662
[ticket/12662] Reorder icon CSS rules alphabetically

Was getting a bit disorganized

PHPBB3-12662
[ticket/12662] Change CSS selectors to direct descendants for linklist

PHPBB3-12662
[ticket/12662] Remove inherited props from ddown-extendended

PHPBB3-12662
[ticket/12662] Fix responsive positioning of notifications dropdown

PHPBB3-12662
[ticket/12662] IE8 fixes

PHPBB3-12662