there is not much magic to it
from PIL import Image
import sys,os
for args in sys.argv[1:]:
for root,dirs,files in os.walk(args):
for f in files:
if f.lower().endswith(".gif"):
im=Image.open(f)
im.save(fn[0:-4]+".png",optimize=False,transparency=0)
if you install python and PIL (or Pillow for python 3) you could just drag and drop a/some folder of images onto the script and it creates png files where it find gif files (overwrittes existing fuiles without conformition)
still think a gui tool is prefered by most but i cant say whats best there