Change LString to use an array of bytes instead of wrapping Java's String.

This brings our implementation more in line with regular C Lua.

src/main/java/lua/value/LDouble.java

@@ -14,8 +14,8 @@ public class LDouble extends LNumber {
 		return (int) m_value;
 	}
 
-	public String luaAsString() {
-		return String.valueOf(m_value);
+	public LString luaAsString() {
+		return LString.valueOf( m_value );
 	}
 	
 	public boolean isInteger() {