Disable history by default

@staticfloat and I noticed that, since julia reads the entire history file on startup, it'll be included in the trace. I'm thinking people might be uncomfortable with having their entire history included in the trace. We should probably consider turning off history by default. Alternatively, we might want to look into a way to sanitize the history and only expose those parts of the history that are actually used.

Start by examining Julia's startup history loading and the trace generation behavior described in the issue. Compare disabling history by default with sanitizing history, and define done as ensuring private history is not exposed in traces while preserving the intended bug-reporting behavior.

Written by the indexing model from the issue text.