Sgtin improvements

[MindWithCake]

I used checked exception for SGTIN parsing errors. Good: can easily check if an EPC is SGTIN encoded with a try-catch, can do that in a Spring Boot application without necessarily triggering a rollback Bad: need to explicitly try-catch the SGTIN parse() call (which imho is still better than having an unhandled runtime exception) TODO: use checked exception when parsing other formats.

PS: I changed the declared JDK version to 9, since the String.chars() method is used in the Converter class

[jlcout]

Hello Ilario!

I quickly looked at your implementation, it was excellent. It's a great addition to the project. At the end of the week I should analyze it in depth and merge it.

PS: Your opinion is very important.

Salute a te e alla tua famiglia.

Thanks.