Respect twocolumn option

Author: haiiliin

README.md

@@ -29,6 +29,7 @@ format:
 
 ## Options
 
+- `twocolumn`: 是否双栏排版，默认为 `true`
 - `eauthor`: 英文作者名字和上标
 - `eaffiliation`: 英文作者单位
 - `eabstract`: 英文摘要

_extensions/chinese-journal/partials/before-body.tex

@@ -1,5 +1,5 @@
 % 生成标题
-\twocolumn
+$if(twocolumn)$\twocolumn$endif$
 \begin{figure*}[t]
 \begin{center}
  \parbox{\textwidth}{

_extensions/chinese-journal/partials/before-title.tex

@@ -67,22 +67,24 @@
 
 % 表格设置
 \usepackage{float,stfloats}
-\makeatletter
-\let\oldlt\longtable
-\let\endoldlt\endlongtable
-\def\longtable{\@ifnextchar[\longtable@i \longtable@ii}
-\def\longtable@i[#1]{\begin{figure}[H]
-\onecolumn
-\begin{minipage}{0.5\textwidth}
-\oldlt[#1]
-}
-\def\longtable@ii{\begin{figure}[H]
-\onecolumn
-\begin{minipage}{0.5\textwidth}
-\oldlt
-}
-\def\endlongtable{\bottomrule\endoldlt
-\end{minipage}
-\twocolumn
-\end{figure}}
-\makeatother
+$if(twocolumn)$
+    \makeatletter
+    \let\oldlt\longtable
+    \let\endoldlt\endlongtable
+    \def\longtable{\@ifnextchar[\longtable@i \longtable@ii}
+    \def\longtable@i[#1]{\begin{figure}[H]
+    \onecolumn
+    \begin{minipage}{0.5\textwidth}
+    \oldlt[#1]
+    }
+    \def\longtable@ii{\begin{figure}[H]
+    \onecolumn
+    \begin{minipage}{0.5\textwidth}
+    \oldlt
+    }
+    \def\endlongtable{\bottomrule\endoldlt
+    \end{minipage}
+    \twocolumn
+    \end{figure}}
+    \makeatother
+$endif$