Description:
------------
Currently, fopen allows you to create new files, but not in directories that don't 
exist - for example, if you want to write to /tmp/logs/something.log, you have to 
check that /tmp/logs exists every time, before running your fopen.

It would be convenient if you could pass a flag to fopen to tell it to recursively 
create any missing directories in the path, in order to open the file.

Test script:
---------------
fopen('/tmp/logs/test.log', 'w'); // fails if logs doesn't exist

mkdir('/tmp/logs');
fopen('/tmp/logs/test.log', 'w'); // fails if logs does exist