fix: EBNF concatenation order

Author: arnaudroques

src/net/sourceforge/plantuml/ebnf/ETileConcatenation.java

@@ -53,6 +53,10 @@ public void push(ETile tile) {
 		tiles.add(0, tile);
 	}
 
+	public void pushLast(ETile tile) {
+		tiles.add(tile);
+	}
+
 	public void overideFirst(ETile tile) {
 		tiles.set(0, tile);
 	}

src/net/sourceforge/plantuml/ebnf/EbnfEngine.java

@@ -122,7 +122,7 @@ public void concatenation() {
 			arg1.push(arg2);
 			stack.addFirst(arg1);
 		} else if (arg2 instanceof ETileConcatenation) {
-			arg2.push(arg1);
+			((ETileConcatenation) arg2).pushLast(arg1);
 			stack.addFirst(arg2);
 		} else {
 			final ETile concat = new ETileConcatenation();