Add a screenshot command.

dcc/ss.py

@@ -0,0 +1,16 @@
+import dcc.config
+import dcc.doom_base
+import wand.image
+
+class SS(dcc.doom_base.WadMap):
+	def get_parser(self, prog_name):
+		parser = super().get_parser(prog_name)
+		parser.add_argument("-g", "--gravity", default="center")
+		return parser
+
+	def take_action(self, parsed_args):
+		with wand.image.Image(width=THUMB_WIDTH, height=THUMB_HEIGHT, pseudo="x:") as img:
+			img.reset_coords()
+			img.crop(width=THUMB_WIDTH,height=THUMB_HEIGHT,gravity="center")
+			img.reset_coords()
+			img.save(filename=dcc.config.BaseThumbPath(parsed_args.wad, parsed_args.map))