Feature: Make requirement for properties to be implemented optional #2
Description
I have a document with property 42 in it.
Currently PROP_LOCK_VISIBILITY is not implemented. https://github.com/FHPythonUtils/GimpFormats/blob/26ee17287e694777b0e8df17aee1a4b8cf9fe8e4/gimpformats/enums.py#L153C4-L153C24
The only thing I want to do with this file is load it to export layers as images.
Currently an Exception is raised: https://github.com/FHPythonUtils/GimpFormats/blob/master/gimpformats/GimpIOBase.py#L514
Perhaps raising a warning the way openpyxl does would be more future-proof? https://foss.heptapod.net/openpyxl/openpyxl/-/blob/10b9879b1f260676b32aa760f77d872436bbe29d/openpyxl/reader/drawings.py#L33