- removing old README file

gh-51 Improved Random Number Generation Performance and add Exponential distribution support (sears)

Remove synchronization points from random number generation.  This mostly consisted switching from per-class instances of Random() that are shared amongst threads to thread-local instances shared across classes.

Also, CounterGenerator.nextInt() was synchronized.  Changed it to use an AtomicInteger.

Finally, removed lastString() from Generator, as it was only called in places where lastInt() was more appropriate; switched the calls to lastInt().

We use FNV hash functions to generate a large indexable sequence of non-colliding keys.  Unforunately, for reasonably sized
workloads, this leads to key collisions, which throws off experiments.

The implementations of the FNV32 and FNV64 hash functions we use manipulate signed integers instead of unsigned integers, so it
is unclear if this is a limitation of the FNV algorithms or of our implementations.

As a workaround, this patch switches from FNV32 to FNV64, reducing the chances of such bad behavior (and eliminating it in our
experiments to date).