Feature Request: Add option to automatically clear cache after a timespan

[ghost]

Hi,

thanks for this nice script, it works great for me. It would be nice to have an option (which could be set in .xscastrc or when the program is invoked in the command line) that automatically clears the cache after a given timespan since the last keypress, emulating a kclear key press after that time.

That way it would be possible when recording screencasts to not think about pressing the kclear key as it would happen automatically.