Enhancement of tx : tx.select(Class<?> cls)

I propose this enhancement, in a transacted select , with possibility of using annotated interface...
like
` .flatMap(tx -> tx.select(Person.class)`
instead of
` .flatMap(tx -> tx.select("select * from person")`
I put it on test in the example bellow and also I am displaying what I've been altering to your code in order for this to work :
`Database.test()`
`.select(Person.class)`
` .parameter(2)`
` .transactedValuesOnly()`
` .get()`
` .flatMap(tx -> tx.update("update person set name=:name where id=:id")`
` .parameter("name", "blabla")`
` .parameter("id", tx.value().id())`
` .transactedValuesOnly()`
` .counts()`
` )`
` .flatMap(tx -> tx.select(Person.class)`
` .parameter(2)`
` .transactedValuesOnly()`
` .valuesOnly()`
` .get()`
` )`
` .subscribe(`
` v -> {out.println(v.name());},`
` e -> out.println(e.getMessage())`
` );`

Here are the modifications I've made to your last version of code (maven 0.2.0 version - thanks for quick publishing btw .. I appreciate it )

in class : org.davidmoten.rx.jdbc.TxWithoutValue
add method :
` TransactedSelectAutomappedBuilder select(Class cls);`
in class : org.davidmoten.rx.jdbc.TxImpl
add method :
` @Override`
` public TransactedSelectAutomappedBuilder select(Class cls) {`
` return db.tx(this).select(cls);`
` }`

in class : org.davidmoten.rx.jdbc.TransactedBuilder
add method :
`public TransactedSelectAutomappedBuilder select(@Nonnull Class cls) {`
` Preconditions.checkNotNull(cls, "cls cannot be null");`
` return new SelectAutomappedBuilder(cls, connections, db).transacted();`
` }`

I am not sure if is error free, I am not familiar with all the options this library has, but if you could look into it would be just great.