Natural comparisons and duplicate file function

Comparisons on files such as xyz9.txt and xyz10.txt would come out as
xyz9.txt being higher and cause issues as startFile and endFile would be
the wrong way round. I'm therefore now comparing on regex replaced
values, where numbers may be prefixed by up to 20 zeros (note
substr(-20) to right align our value.
delete, copy and paste file functions now plural as they handle multiple
files.
copyFiles works with a given fileList and not just the selectedFiles
array. Also passing params to control if we hide or show paste option
and file menu
pasteFiles will refuse to paste the root, that would cause bad looping &
compound pasting issues
duplicateFiles function added which takes a snapshot of the copiedFiles
array, copies the files while not showing paste menu or hiding menu. It
then sets the paste location to be the parent of the duplicate target
and pastes into that location. Once done copiedFiles is returned to the
snapshot image.
Open and Duplicate options plus hr breaks

HR added to file menu to break it up into logical sections
openFilesFromList is more accurate function name now
copyFiles and deleteFiles now has selectedFiles array passed as param
duplicateFiles is a new option added between these
No need to unset selectedFiles on new paste