cmm: splitted commands into separate modules (and more cleanup)

chatmastermind/commands/print.py

@@ -0,0 +1,19 @@
+import sys
+import argparse
+from pathlib import Path
+from ..configuration import Config
+from ..message import Message, MessageError
+
+
+def print_cmd(args: argparse.Namespace, config: Config) -> None:
+    """
+    Handler for the 'print' command.
+    """
+    fname = Path(args.file)
+    try:
+        message = Message.from_file(fname)
+        if message:
+            print(message.to_str(source_code_only=args.source_code_only))
+    except MessageError:
+        print(f"File is not a valid message: {args.file}")
+        sys.exit(1)