Topobank-publication

- BUG: Fixed version discovery

- BUILD: Changed build system to flit

- MAINT: Compatibility with topobank 1.7.0

- MAINT: Fixed typo in publishing screen

- ENH: /go links return API redirect if `application/json` is requested,
otherwise HTML redirect (9)
- ENH: API endpoint for publication now returns download link
- BUG: Fix to /go links (8)
- MAINT: Adding gitignore

- MAINT: Split `publication` module from main TopoBank
- MAINT: Enforcing PEP-8 style