*FIX : gdcmHeader::LoadElements is now based

  *FIX : gdcmHeader::LoadElements is now based
             on the ListTag listElem member,
             not longer on the TagElValueHT tagHt member
      *ENH : PrintPubElVal shows (temporarily) both results,
             with the tagHt member and the listElem member.
	     (it's easier to 'see' the problems when using Printheader)

      *FIX : old private member LgrElem is now splitted into
             ReadLength   : Length actually found on disk (updated only
	                    if bug fixing is necessary), for internal
			    use only
	     UsableLength : Updated by FixFoundLength, to fix a bug
	                    or to allow Parser going on.
	     Will allow to re-write a kosher header when a SeQuence
	     with a length (not 0000) is found
      Warning : gdcmFile::Write still uses the TagHt (not ListElem)
	        because gdcmElValSet::Add does not update ListElem
		(to be written)