handle atotm parse error
fixed localtime cacheing
(cd) automatically add slash if needed.
(UpdateFileSet) new method; use it.
(AddFirst, GetFirstType) new methods.
add mirror --file/-f and --target-directory/-O options.
allow IOBufferFileAccess creation with plain pointer.
	* Http.cc, Http.h: don't log empty commands;
	  handle PROPFIND result of CHANGE_DIR op; add "quote PROPFIND" support
	  (mostly for debugging); don't send Content-Type for PROPFIND requests
	  if there is no request body; don't request file info if not needed in
	  ARRAY_INFO mode.
	* HttpDir.cc: automatically detect xml file listing.
	* HttpDirXML.cc: handle atotm errors.