Implement support for multiple attributes

[andy5995]

Looking at dnsmasq.conf.example I see it uses multiple attributes (strings following commas). Right now, canfigger only supports one. I was thinking that would probably be a good change to add.

@eteran, For the attribute member of the struct, do you think a c-vector would be a good choice for the data type?

The other option is I could make another node type that would wind up being a linked list to each attribute in the main node, but that seems like overkill.

What do you think?

[andy5995]

I decided to just add another linked list for the attributes and avoid adding external dependencies.

[eteran]

@andy5995 c-vector is certainly a reasonable choice anywhere you want a flexible array. However, for your use case, a linked list seems simple enough :-)

[andy5995]

Thanks for the feedback @eteran