expand_relative_paths has to be set before parse is called.

[mbakeranalecta]

If you set expand_relative_paths on the parser after calling samParser.parse, it will have no effect. This is because it gets passed to the DocStructure object when it is created.

Probably not a good idea to have expand_relative_paths be a property of the doc structure at all. But then have to deal with the fact that the doc structure is only created when the parse method is called. Maybe that should change too, so that the doc object is created when the parser is created, allowing us to immediately set properties on it.

Alternatively, if it seems like the properties intuitively belong to the parser, maybe we need to let them be read from block in the doc structure.