Added SymbolTable interface for future implementation

SymbolTable.java

@@ -0,0 +1,17 @@
+public class SymbolTable {
+	public boolean isDeclared(String symbol, int current_level) {
+		return false;
+	}
+	public void insert(String symbol, boolean ref, int current_level) {
+
+	}
+
+	public boolean search(String symbol, boolean ref) {
+
+		return false;
+	}
+
+	public void destroy(int current_level) {
+
+	}
+}