move shell interpreter to own file

bs.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+"""Interactive BaconScript shell.
+"""
+
+import sys
+from bacon.script import comment
+
+# handle user input if run directly
+if __name__ == '__main__':
+    if len(sys.argv) > 1:
+        # look for macros passed as arguments
+        logger.debug("found macro at argv[1]")
+        comment(sys.argv[1])
+    else:
+        # for input history and line editing
+        import readline
+        # be an interactive shell
+        while True:
+            # get user input
+            try:
+                text = input("comment# ")
+            except (KeyboardInterrupt, EOFError):
+                text = 'exit'
+                print(text)
+            # catch exit keyword
+            if text.lower() == 'exit':
+                break
+            # exec user input
+            comment(text)