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.
m_err_count should be int to handle reduction