AsciiDoc writer: use doubled delims in more contexts.

Also escape the `#` character.

Closes #11362.

An alternative solution, raised in #11362, would be to
rely less on escaping and simply always use doubled delimiters.
However, there would still be a need for escaping, since one
might use a literal `##` (for example)>

1 files changed, 17 insertions, 0 deletions

diff --git a/test/command/11362.md b/test/command/11362.md
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@@ -0,0 +1,17 @@
+```
+% pandoc -f markdown -t asciidoc
+This is a _test_[^1].
+
+And yet another **one**[^1].
+
+We can also try to write #hashtags [this]{.test}.
+
+[^1]: Test footnote.
+^D
+This is a __test__footnote:[Test footnote.].
+
+And yet another **one**footnote:[Test footnote.].
+
+We can also try to write ++#++hashtags [.test]#this#.
+
+```