Add a check command.

dcc/check.py

@@ -0,0 +1,10 @@
+import dcc.config
+import dcc.doom_base
+import wand.display
+import wand.image
+
+class Check(dcc.doom_base.WadMap):
+	def take_action(self, parsed_args):
+		with wand.image.Image(filename=dcc.config.BaseThumbPath(parsed_args.wad, parsed_args.map)) as img:
+			print("Image is {}x{}.".format(img.width, img.height))
+			wand.display.display(img)

setup.py

@@ -27,6 +27,7 @@ setup(
 			'put = dcc.put:Put',
 			'pb = dcc.pb:PB',
 			'ss = dcc.ss:SS',
+			'check = dcc.check:Check',
 		],
 	},
 	zip_safe=False,