Enormous Performance Improvements!

I am proud to announce that the latest patch of this library has improved the performance terrificly.
Just look at the benchmark differences:

v1.1.0 benchmarks:

BenchmarkEncoder64_DecodeNum-8         4412131           275 ns/op
BenchmarkEncoder64_DecodeLong-8          90235         13410 ns/op
BenchmarkEncoder64_EncodeNum-8         3947503           298 ns/op
BenchmarkEncoder64_EncodeLong-8          66300         18054 ns/op

vs the previous

v1.0.0 benchmarks:

BenchmarkEncoder64_DecodeNum-8          333340          3528 ns/op
BenchmarkEncoder64_DecodeLong-8           6667        183585 ns/op
BenchmarkEncoder64_EncodeNum-8          244857          4991 ns/op
BenchmarkEncoder64_EncodeLong-8           3634        342039 ns/op

(tested on the same system: Intel Core i7 4790k @ 4.00GHz)