Following the new naming guidelines.

All projects (and namespaces) should start with an "ATx" prefix, having
a capital "AT" and a lowercase "x".

Since we have more to share between the applications than just the XML
wrappers, this is the location to keep common classes and methods.

Refers to #2

Fixes #22

Note that this only adds the new class library, it does not yet adjust
the existing service code to use it!

Refers to #21

Corresponds to "autotransfer-v1".