This fixes various issues relating to how input whitespace is handled
and how wrapping handles whitespace resulting from hard line breaks.
This PR uses a branch based on that for #120 to avoid conflicts with
the fixes and associated test changes there. My suggestion is thus
first to merge #120 (which fixes two open issues), then to merge the
remaining changes from this PR.
Wrapping paragraphs has the effect of losing all newlines including
those from `<br>` tags, contrary to HTML semantics (wrapping should be
a matter of pretty-printing the output; input whitespace from the HTML
input should be normalized, but `<br>` should remain as a hard line
break). To fix this, we need to wrap the portions of a paragraph
between hard line breaks separately. For this to work, ensure that
when wrapping, all input whitespace is normalized at an early stage,
including turning newlines into spaces. (Only ASCII whitespace is
handled this way; `\s` is not used as it's not clear Unicode
whitespace should get such normalization.)
When not wrapping, there is still too much input whitespace
preservation. If the input contains a blank line, that ends up as a
paragraph break in the output, or breaks the header formatting when
appearing in a header tag, though in terms of HTML semantics such a
blank line is no different from a space. In the case of an ATX
header, even a single newline appearing in the output breaks the
Markdown. Thus, when not wrapping, arrange for input whitespace
containing at least one `\r` or `\n` to be normalized to a single
newline, and in the ATX header case, normalize to a space.
Fixes#130
(probably, not sure exactly what the HTML input there is)
Fixes#88
(a related case, anyway; the actual input in #88 has already been fixed)
