DolphinTool: Add an image extract command

Readme.md

@@ -193,7 +193,7 @@ is intended for debugging purposes only.
 ```
 usage: dolphin-tool COMMAND -h
 
-commands supported: [convert, verify, header]
+commands supported: [convert, verify, header, extract]
 ```
 
 ```
@@ -252,3 +252,22 @@ then exit.
                         Optional. Print the level of compression for WIA/RVZ
                         formats, then exit.
 ```
+
+```
+Usage: extract [options]...
+
+Options:
+  -h, --help            show this help message and exit
+  -i FILE, --input=FILE
+                        Path to disc image FILE.
+  -o FOLDER, --output=FOLDER
+                        Path to the destination FOLDER.
+  -p PARTITION, --partition=PARTITION
+                        Which specific partition you want to extract.
+  -s SINGLE, --single=SINGLE
+                        Which specific file/directory you want to extract.
+  -l, --list            List all files in volume/partition. Will print the
+                        directory/file specified with --single if defined.
+  -q, --quiet           Mute all messages except for errors.
+  -g, --gameonly        Only extracts the DATA partition.
+```