Issue #10250: Enable "Layers as Pages" for single layer group in PDF export
This patch attempts to resolve #10250 (closed).
When saving a PDF, you have the option to export layers as pages. This still works if there is single layer group that contains multiple layers. However, the option is disabled because the plug-in only checks "top level" layers.
This patch adds code to check if the single layer is a layer group, then enables the option if there are more than one layer in that group.
If approved, this could be easily backported for 2.10.36.