v0.1.0 about bitset

[kawasin73]

Benchmark

• OS : macOS Sierra 10.12.6（16G1618）
• PC : MacBook Pro (Retina, 13-inch, Early 2015)
• CPU : 3.1 GHz Intel Core i7
• Mem : 16 GB 1867 MHz DDR3

$ go test -bench=.
goos: darwin
goarch: amd64
pkg: github.com/kawasin73/bibit
BenchmarkBitVec_Set_LittleEndian-4     	300000000	         5.15 ns/op
BenchmarkBitVec_Set_BigEndian-4        	100000000	        13.1 ns/op
BenchmarkBitVec_Unset_LittleEndian-4   	300000000	         5.20 ns/op
BenchmarkBitVec_Unset_BigEndian-4      	100000000	        13.2 ns/op
BenchmarkBitVec_Get_LittleEndian-4     	300000000	         4.34 ns/op
BenchmarkBitVec_Get_BigEndian-4        	200000000	         8.00 ns/op
BenchmarkSwap-4                        	2000000000	         1.14 ns/op
PASS
ok  	github.com/kawasin73/bibit	13.474s