v0.4.0

raindrops 0.4.0 - flowing into new systems!

Non-GCC 4.x users may use the libatomic_ops[1] package to
compile Raindrops.  Memory efficiency is improved for modern
glibc users with run-time cache line size detection, we no
longer assume 128 byte cache lines.

[1] - http://www.hpl.hp.com/research/linux/atomic_ops/