Unexpected behaviour when entering percentage values in EditableInput
I have noticed some non intuitive behavior when entering values into EditableInputs that are expecting percentage values (for example Saturation and Luminosity).
If the user doesn't delete the existing percentage sign and overwrites the numeric value it will snap to 0%.
Similarly if the user deletes the entire contents of the field, then enters a value followed by a percentage sign the value will snap to 0%.

I believe this is due to the `EditableInput.handleChange()` attempting to parse a string with a percentage value as a number, failing and producing NaN instead. I will open a pull request that I believe fixes this issue soon.