remove duplicate files for specified ext types

Usage examples:

• generate a .bat file for removing all duplicate files(keep the first one) in all disks

python rmAllDupByExt.py

• generate a .bat for removing duplicate files in the given directory

python rmAllDupByExt.py -d D:\test

• removing all duplicate files(keep the first one) in all disks

python rmAllDupByExt.py -rm

• removing duplicate files in the given directory

python rmAllDupByExt.py -d D:\test -rm