Smarter rebalacing avoiding double checking
Smarter rebalacing avoiding double checking

benchmark                              old ns/op     new ns/op     delta
Benchmark_10values_windowsize1         989           896           -9.40%
Benchmark_100values_windowsize10       15814         15213         -3.80%
Benchmark_10Kvalues_windowsize100      2386735       2372705       -0.59%
Benchmark_10Kvalues_windowsize1000     2973423       2935589       -1.27%

JaderDias/movingmedian