Update benchmarks

[benalexau]

I'd like to revisit the LmdbJava Benchmarks with current JVMs to quantify the cost-benefit analysis of buffer reuse. It's also a good chance to update the third party key-value store versions and any new projects which can be easily added.

I also note there's a Java Native Benchmark which compares the major native library access technologies (including JNR). It'd be useful to do something similar for a simple LMDB use case that includes requisite buffer allocation, deallocation and potential reuse.

The overall objective is to better understand the options available to progress #42.