Allow optional arguments to LaTeX macros to span lines. This is legal in

LaTeX and we have at least one occurance of that in the content, so this
script needs to support it as well.

Doc/tools/sgmlconv/latex2esis.py

@@ -56,7 +56,7 @@ _end_env_rx = re.compile(r"[\\]end{([^}]*)}")
 _begin_macro_rx = re.compile(r"[\\]([a-zA-Z]+[*]?) ?({|\s*\n?)")
 _comment_rx = re.compile("%+ ?(.*)\n[ \t]*")
 _text_rx = re.compile(r"[^]~%\\{}]+")
-_optional_rx = re.compile(r"\s*[[]([^]]*)[]]")
+_optional_rx = re.compile(r"\s*[[]([^]]*)[]]", re.MULTILINE)
 # _parameter_rx is this complicated to allow {...} inside a parameter;
 # this is useful to match tabular layout specifications like {c|p{24pt}}
 _parameter_rx = re.compile("[ \n]*{(([^{}}]|{[^}]*})*)}")