Problem with <hr> in LaTeX multicolumn cell

In case we have a `<hr>` in a table cell then it is displayed as a horizontal line (in LaTeX) unless it is in a multicolumn cell. In the later case it throws an error:
```
! You can't use `\hrule' here except with leaders.
\DoxyHorRuler ... }{0ex plus 0ex minus 0ex}\hrule
```

We have to use use `\hrulefill` in a table but in combination with the table option of xcolor this gives some problems so a new command has to be defined for this.

See also:
- horizontal rule / line inside a multicolumn field (https://tex.stackexchange.com/questions/506211/horizontal-rule-line-inside-a-multicolumn-field)
- interaction between \usepackage[table]{xcolor} and \hrulefill (https://tex.stackexchange.com/questions/506221/interaction-between-usepackagetablexcolor-and-hrulefill)

src/latexdocvisitor.cpp

@@ -280,7 +280,10 @@ void LatexDocVisitor::visit(DocLineBreak *)
 void LatexDocVisitor::visit(DocHorRuler *)
 {
   if (m_hide) return;
-  m_t << "\\DoxyHorRuler\n";
+  if (insideTable())
+    m_t << "\\DoxyHorRuler{1}\n";
+  else
+    m_t << "\\DoxyHorRuler{0}\n";
 }
 
 void LatexDocVisitor::visit(DocStyleChange *s)

templates/latex/doxygen.sty

@@ -35,9 +35,19 @@
   \endgroup%
 }
 
-\newcommand{\DoxyHorRuler}{%
+\makeatletter
+\newcommand\hrulefilll{\leavevmode\leaders\hrule\hskip 0pt plus 1filll\kern\z@}
+\makeatother
+
+\newcommand{\DoxyHorRuler}[1]{%
   \setlength{\parskip}{0ex plus 0ex minus 0ex}%
-  \hrule%
+  \ifthenelse{#1=0}%
+  {%
+    \hrule%
+  }%
+  {%
+    \hrulefilll%
+  }%
 }
 \newcommand{\DoxyLabelFont}{}
 \newcommand{\entrylabel}[1]{%