The goal is to be able to form bundle value paths like `Group/Sub/Geometry` in
the future. Additionally we might want to be able to use these paths in some
kind of expression for selecting a set of bundle paths. This requires us to
constrain what characters are allowed to be used in bundle paths. This patch
forbids using various special characters. Since we don't know exactly which
characters we'll need exactly in the future, I added more characters to the
forbidden-list than likely necessary. It's easier to make them available later
on than to try to forbid them later.
The forbidden chars are the following currently:
`/*&|"^~!,{}()+$#@[];:?<>.-%\=`.
Those are automatically replaced by an underscore if used.
Pull Request: https://projects.blender.org/blender/blender/pulls/142168
cbb76f21a1