v2.17.0

Read a large sheet a row at a time, without building the cell grid.

New

• Excel.streamRows(sheetName) walks a worksheet row by row straight out of the
  archive, yielding List<CellValue?> without materialising the sheet's cell
  grid. Excel.streamRowsAsMaps(sheetName) does the same keyed by a header row.
  On a 2.5 MB sheet of 40,000 rows this measured 94 MB of additional memory
  against 164 MB for the eager path, and ran about 30% faster. The saving grows
  with row count, because the streaming cost is dominated by the worksheet XML
  rather than by the number of cells.
• The iterable is lazy. Breaking out of the loop stops the parse there instead
  of after the whole file has been read, which is what you want when validating
  a bulk upload and rejecting on the first bad row.

Values are typed exactly as the ordinary reader types them. Both paths now share
one decoder, and a test asserts they return identical values for every sheet of
a real file, so the two cannot drift apart. Styles, merges and row metadata are
not read on the streaming path; use the ordinary path when you need those.