Markdown writer adds improper escaping to "a)" at beginning of paragraph

[jgm]

The culprit is a very old commit, a70c2b2. The markdown writer looks to see if the paragraph begins with something that might be mistakenly interpreted as an ordered list, and escapes it with a backslash. The problem is that the markdown reader interprets \a) as a latex command followed by ), and only ) appears if we again read the markdown that we wrote.

One solution would be to escape all periods and parens, but that is drastic and ugly.

Better: look in the inline list before conversion. Still a bit tricky.

Test case:

pandoc -t markdown
a\) one

b\) two
^D
\a) one

\b) two