version bump 0.6.2: bits reorganization

- updated SSF to 0.6.5
- XLSB 'dbcs' uses codepage
- README bugfix (h/t @noodles)
- new tests: rawjson and json baselines generated by hand
- single cell ranges are encoded as cells ("A1" instead of "A1:A1") (h/t @clxl)
- source code alignment with js-xls