Added support for setting separator from string.

Flux cannot set option values of type char. This commit adds a
setSeparator method which uses the first character of a string as
separator. If the string is empty, then then separator is reset to its
default value.

Author: cboehme

src/main/java/org/culturegraph/mf/stream/converter/RecordReader.java

@@ -51,6 +51,14 @@ public final class RecordReader extends
 	private char separator = DEFAULT_SEPARATOR;
 	private boolean skipEmptyRecords = true;
 
+	public void setSeparator(final String separator) {
+		if (separator.length() >= 1) {
+			this.separator = separator.charAt(0);
+		} else {
+			this.separator = DEFAULT_SEPARATOR;
+		}
+	}
+
 	public void setSeparator(final char separator) {
 		this.separator = separator;
 	}