Apparently the in-line link syntax with "<>" in them causes these warnings. I
don't know why. I changed them all to a slightly more verbose syntax.
Thanks to Mike Kazantzsev's review comment
(https://github.com/tahoe-lafs/tahoe-lafs/pull/67#commitcomment-4561370), I
moved the links to the end of each section.
Add ".. -*- coding: utf-8-with-signature -*-" to the first line of each .rst
file. This tells emacs to treat the file contents as utf-8, and also to prepend
a so-called utf-8 "bom" marker at the beginning of the file. This patch also
prepends those markers to each of those files.
interfaces.py: modified the return type of RIStatsProvider.get_stats to allow for None as a return value
NEWS.rst, stats.py: documentation of change to get_latencies
stats.rst: now documents percentile modification in get_latencies
test_storage.py: test_latencies now expects None in output categories that contain too few samples for the associated percentile to be unambiguously reported.
fixes#1392
