Make folder path selectable in FireFox

Make the folder name and the folder path selectable in FireFox, as discussed here: https://pulse-forum.ind.ie/t/how-can-the-folder-path-be-changed/1153/6

Add the assets to the commit
Add me to the contributors
Add me to the contributors in the index.html
Populate block offsets even if the blocks are not diffed
Fix blockmap hash size
Refinements to UPnP documentation
UPnP API for querying of services' external IP address
Merge branch 'pr/875'

* pr/875:
  Make folder path selectable in FireFox
Enable portmapping for individual UPnP services
Merge pull request #876 from cqcallaw/upnp

UPnP API Additions to address outstanding parts of #432
Upgrade test configs to v6
Devices added by introducer should have dynamic address (fixes #866)
Translation update
OpenBSD support (fixes #878)
Remove 64 device limit
Merge pull request #886 from AudriusButkevicius/limit

Remove 64 device limit
Fix error messages
Add test for syncing with 100 configured devices
Update xdr; handle marshalling errors
Move recurring UPnP log messages to debug level
Add -logfile flag, Windows only
Write Windows line breaks on Windows; tee to stdout