Do not serialize the status XML if the actual value of ServiceSuspended
and / or LimitReason has not really changed. This effectively prevent
the "heartbeat" value (LastStatusUpdate) from being updated once per
AutoTx timer cycle.

Closes #19

Refers to #26

Having the total progress is much more useful than for the individual
files, especially for transfers with many files.

Closes #26

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

All outputs of any kind of duration should be using a human readable
variant of the time span.

Fixes #25

With proper logging in place this is now easily doable, therefore we
don't need the "ValidationWarnings" workaround any more.

Refers to #3

Refers to #3

Refers to #3

Currently this is almost entirely untested and configuration for email
notifications is yet to be done.

Refers to #3

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

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

Refers to #21

An email will be sent only if the time since the last one exceeds the
new configuration option "GraceNotificationDelta", defaulting to 12
hours.

Fixes #1

Corresponds to "autotransfer-v1".