Rewrote grammar, implemented two visitors

src/main/java/de/hsrm/compiler/Klang/Value.java

@@ -0,0 +1,55 @@
+package de.hsrm.compiler.Klang;
+
+public class Value {
+
+  public static Value VOID = new Value(new Object());
+
+  final Object value;
+
+  public Value(Object value) {
+      this.value = value;
+  }
+
+  public Integer asInteger() {
+    return (Integer)value;
+  }
+
+  public String asString() {
+      return String.valueOf(value);
+  }
+
+  public boolean isDouble() {
+      return value instanceof Double;
+  }
+
+  @Override
+  public int hashCode() {
+
+      if(value == null) {
+          return 0;
+      }
+
+      return this.value.hashCode();
+  }
+
+  @Override
+  public boolean equals(Object o) {
+
+      if(value == o) {
+          return true;
+      }
+
+      if(value == null || o == null || o.getClass() != value.getClass()) {
+          return false;
+      }
+
+      Value that = (Value)o;
+
+      return this.value.equals(that.value);
+  }
+
+  @Override
+  public String toString() {
+      return String.valueOf(value);
+  }
+}