Unable to export image by with picture area size

[dmitry-t]

Exported images may be greater than the picture size if "Crop to drawn bounds?" is unset.

There is an error, the option should be "-C", not "C": https://github.com/jespino/inkscape-export-layers/blob/1d3a096420a5403f7d54a50aec3dcf2ea1521824/export_layers.py#L94