Refactor exit_code implementation

cmd2.Cmd.cmdloop() now returns self.exit_code which should be an integer

Also:
- Refactored examples to call sys.exit(app.cmdloop()) in their __main__
- Running transcript tests now sets the exit_code accordingly based on success/failure
- Updated CHANGELOG
- Updated README
- Updated Sphinx docs
- Added unit test for case when transcript test fails

1 files changed, 2 insertions, 2 deletions

diff --git a/examples/environment.py b/examples/environment.py
index e899cce8..9e611f08 100755
--- a/examples/environment.py
+++ b/examples/environment.py
@@ -3,7 +3,6 @@
 """
 A sample application for cmd2 demonstrating customized environment parameters
 """
-
 import cmd2
 
 
@@ -34,5 +33,6 @@ class EnvironmentApp(cmd2.Cmd):
 
 
 if __name__ == '__main__':
+    import sys
     c = EnvironmentApp()
-    c.cmdloop()
+    sys.exit(c.cmdloop())