SpanMode uses incorrect terminology (breadth)

[Ben Davis]

According to http://dlang.org/phobos/std_file.html :

depth
Spans the directory depth-first, i.e. the content of any subdirectory is 
spanned before that subdirectory itself. Useful e.g. when recursively 
deleting files.

breadth
Spans the directory breadth-first, i.e. the content of any subdirectory 
is spanned right after that subdirectory itself.

That's not what breadth-first means at all. See 
http://en.wikipedia.org/wiki/Tree_traversal which has the correct 
definition: breadth-first means ALL directories at one level are 
returned before ANY child of ANY directory is considered.

Wikipedia uses the terms preorder and postorder for what's intended 
here, but those are a bit obtuse. Something like parentFirst and 
childrenFirst would get the message across clearly.

I don't much mind what the names change to, but the current completely 
wrong situation really irks me! Deprecate it at once! :P

Ben :)