Scala import - handle <inactive>

[SeanArchibald]

https://modwiggler.com/forum/viewtopic.php?p=3703023

In an scl file some lines can have an <inactive> handle. We need to investigate what to do with these lines when importing an scl file as currently they are not handled.

[vsicurella]

Being able to handle these lines would bring us a step closer to being supporting custom note labels, something @meszaros-lajos-gyorgy has suggested before