Allow setting the log level explicitly from "Warn", "Info", "Debug" or
"Trace" in the configuration.

Default is "Info", fallback for invalid settings is "Debug".

Fixes #34

Refers to #18, #29

Refers to #28

Refers to #29

Refers to #29

Refers to #18

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

Using an optional element in the configuration XML, defaulting to "true"
via the configuration class constructor.

Refers to #16

The method checks folders in the grace location for their age (parsing
the folder name timestamp) and generates a report for those older than
the given GracePeriod.

This is related to issue #1

Corresponds to "autotransfer-v1".