Make it default to overwrite existing files instead of throwing an Error

[xgdgsc]

Currently it shows error like:

Error encountered while saving "results/rob/gp_2019-01-27-13-13_1_mr01.xlsx".
Fatal error:
ERROR: LoadError: AssertionError: results/rob/gp_2019-01-27-13-13_1_mr01.xlsx already exists.
Stacktrace:

when file exists. Is there an option to overwrite? Most saving utilities I use overwrite files by default, like CSV and JLD2.

[davidanthoff]

Yeah, adding an option that allows overwriting would be good!