Fixes for FileUtills::CreateDirectory().

This commit makes FileUtills::CreateDirectory() return a short, and
makes it's createRecursive bool a constant reference.

This commit also makes a copy of the FileUtills::CreateDirectory()
function that does not need a Panic::ERROR object.

(Also the function comments for FileUtills::CreateDirectory() were
updated.)

Sidenote: Looking back on this I'm supprised that this works at all, I
really need to rewrite this stuff. (Then again, I wrote it over 2 years
ago....)