v0.21.3

Fixed

Spreadsheet pages read the way a model is laid out:

• A note beside an input stays with it. A column of text beside a
  block, on rows the block fills, joins it even across an empty column, and
  a label and value with notes reads Label: value — note. It used to be cut
  off into a list of its own after the inputs.
• A table split by empty rows keeps its header. A table whose first row
  is data, written with a currency, a percent, a fraction or more than four
  digits, takes the header of the table above it on the same columns, and
  its formulas are named by that header. It used to take its first row of
  data for a header. A header of years is still a header.
• A sentence on its own line is a paragraph. A caption is a heading when
  it is at most 80 characters and does not end like a sentence.
• An empty column a block spans is no column of its table.

sheetVersion moves to 2, so the next sync reads every spreadsheet again
once, unchanged uploaded files included.