Save button

[etfz]

I previously request that it be possible to always save coordinates by default. I now realise why it would not always be the preferred behavior. (initial setup vs existing topology)
#120 (comment)

However, I think the better solution would actually be to have a Save button and require explicit saving. The existing option could then simply be used as auto save. I think this would be much more intuitive than having the option on the filters tab.