update URL with filename via pushState
consolidate filename subscribe with other call
Revert "consolidate filename subscribe with other call"

This reverts commit f43d0201995c4ddbdbdcaf855f64933237f095d0.
on page load, load worksheet by filename specified in URL anchor
attempt to highlight last segment, even when file loaded
fixed last (empty) segment to be highlighted as active on URL-based file load
after loading file manually, store filename in URL
Merge pull request #3 from modellurgist/show-filename-as-url-anchor

Show filename as url anchor