Improved microbenchmarking with multiple features.

* inline performance critical code
* Average runtime is specified and used to calculate iterations.
* Console: show median of multiple runs
* plot: show box plot
* filter benchmarks
* specify scaling factor
* ignore src/test and src/bench in command line check script
* number of iterations instead of time
* Replaced runtime in BENCHMARK makro number of iterations.
* Added -? to bench_bitcoin
* Benchmark plotly.js URL, width, height can be customized
* Fixed incorrect precision warning

src/bench/base58.cpp

@@ -54,6 +54,6 @@ static void Base58Decode(benchmark::State& state)
 }
 
 
-BENCHMARK(Base58Encode);
-BENCHMARK(Base58CheckEncode);
-BENCHMARK(Base58Decode);
+BENCHMARK(Base58Encode, 470 * 1000);
+BENCHMARK(Base58CheckEncode, 320 * 1000);
+BENCHMARK(Base58Decode, 800 * 1000);