WIP: Update to v0.8

Update to v0.8, based on previous work by @ah.

This MR specifically does not switch to Python 3, since that implies a trip through NEW. I'm going to prepare a separate MR for that, so that we can get some testing of v0.8 while we're waiting for NEW approval.

Fixes:

• #951619: New upstream release
• #909564: Support local-only services via the loopback interface

Might fix:

• #876107: UnicodeDecodeError: 'ascii' codec can't decode byte 0xc2 in position 20: ordinal not in range(128)

/cc @biebl @bigon @ah