Various fixes to operator preset cleanup:
- Only remove properties that match exactly the properties to exclude
exactly (taking word boundaries into account).
- When the preset path doesn't exist, don't construct paths relative
to the working directory.
- Enforce UTF8 encoded text.
Other minor changes:
- Rename "properties" to "properties_exclude" for clarity.
- Use single underscore for private methods.
- Match each line against a single regex instead of constructing a
string and checking startswith(..) for every property to exclude.
- Use os instead of pathlib, as us used in blender's built in operators
that handle paths.
- Prefer doc-string over bl_description.
- Double quote strings.
- Use single indentation for lists to reduce right-shift.
d5598838a2