v0.33.0

As major releases go, this is pretty minor. To use this release, you need to modify
your startup.py scripts, for the default workspace and for any
workspaces you have created. (The default startup file is most likely location
is ~/.config/marcel/workspace/__DEFAULT__/startup.py. For a workspace named foobar, it's
~/.config/marcel/workspace/foobar/startup.py).

In your startup scripts make the following changes:

1. Change PROMPT = (...) or PROMPT=[...] to set_prompt(...).
2. Delete the PROMPT_CONTINUATION assignment statement.