(refs #445)Keep line separator in online file editing

src/main/scala/util/StringUtil.scala

@@ -46,6 +46,22 @@ object StringUtil {
       }
     }
 
+  /**
+   * Converts line separator in the given content.
+   *
+   * @param content the content
+   * @param lineSeparator "LF" or "CRLF"
+   * @return the converted content
+   */
+  def convertLineSeparator(content: String, lineSeparator: String): String = {
+    val lf = content.replaceAll("¥r¥n", "¥n").replaceAll("¥r", "¥n")
+    if(lineSeparator == "CRLF"){
+      lf.replaceAll("¥n", "¥r¥n")
+    } else {
+      lf
+    }
+  }
+
   /**
    * Extract issue id like ```#issueId``` from the given message.
    *