Merge pull request#3 from jsonjoy-com/perf-writerPerf writer

Merge pull request#2 from jsonjoy-com/buf-slicefeat: 🎸 add `.subarray()` method

Merge pull request#1 from jsonjoy-com/slicesfeat: 🎸 add .slice() and .cut() methods

test: 💍 pass test