Move template parameter in Thread to a more logical scope location.
Generalize unlink to OS-dep code in Utils, just a little prep for Windows port.
Actually report a meaningful network status instead of always OK
Back off a little on multicast propagation depth. Eventually this will be a network parameter.
Add RateLimiter for rate limiting multicast, not tested yet.
Add a concept of debt to RateLimiter, save a bit of RAM.
Tweak default multicast rate limits.
Fix for another wonderful C++ threading race condition.
Version 0.4.1 - RateLimiter for multicast, bug fixes.

This version adds a draft of the multicast rate limiting architecture. A
few minor bugs are also fixed. The Linux version builds in debug mode for
now.