* nickvergessen/ticket/develop/10345: (21 commits) [ticket/10345] Check directly whether the key to use exists [ticket/10345] Return the language key when the key has an empty array [ticket/10345] Document behaviour for floating numbers on phpbb_get_plural_form [ticket/10345] Remove doubled check for valid plural rule [ticket/10345] Add documentation and phpbb_ prefix to the new avatar functions [ticket/10345] Add cases for 1 pixel height on MAX_FLASH and MAX_IMG sizes [ticket/10345] Fix parsing error in language/en/viewtopic.php [ticket/10345] Move rule determination code into a new function [ticket/10345] Fix little type in unit test [ticket/10345] Remove more useless 0-cases [ticket/10345] Make the use of the 0-case optional [ticket/10345] Remove some unused 0 cases [ticket/10345] Fix some last use cases of sprintf() to use $user->lang() [ticket/10345] Add tests for array() as first parameter on call to $user->lang() [ticket/10345] Fix some documentation issues. [ticket/10345] Allow float as array key and add some tests [ticket/10345] Use the plural function in some more places. [ticket/10345] Make use of the plural function in some basic places [ticket/10345] Remove '1 hour ago' string which conflicted with plural rules [ticket/10345] Fix documentation on the new function and the switch ...