Merge pull request #774 from python-cmd2/completion_state

Completion state

Author: tleonhardt

CHANGELOG.md

@@ -5,6 +5,10 @@
 * Enhancements
     * No longer treating empty text scripts as an error condition
     * Allow dynamically extending a `cmd2.Cmd` object instance with a `do_xxx` method at runtime
+    * Choices/Completer functions can now be passed a dictionary that maps command-line tokens to their
+    argparse argument. This is helpful when one argument determines what is tab completed for another argument.
+    If these functions have an argument called `arg_tokens`, then AutoCompleter will automatically pass this
+    dictionary to them.
 
 ## 0.9.16 (August 7, 2019)
 * Bug Fixes