Add util.* for recent changes. Don't need bttime.h in downloader.cpp.
Clean up time headers
Abstract precision timer calls.
Abstract and unify use of random bits. Change client version for ongoing work.
Create maintenance branch for 3.x
tag dtorrent-3.3 (ctorrent-dnh3.3)
dnh3.3 release update
Include config.h in bitfield.cpp
Support systems that do not supply random(3).
Fix unlikely but potential division by zero in Prefetch.