ByteBuffer pool

[rschildmeijer]

The discoveries that were found in # 81 made me curios about introducing a ByteBuffer pool (experimental). Design aspects: Pool.allocate(int requestedCapacity) will always return a bb with capacity >= requestedCapacity. If no vacant bb is present a new bb will be allocated. To void ugly "!= null" checks in the "pool client" code.

The characteristics of the pool should be configurable by the end user (e.g max pool size, both by # of bb and by mb (total size) (inspired by memtable configuration in apache cassandra)).