+ Added an empty Import menu item
* Moved the Data Directory stuff to a new class
+ Began adding an Import dialog
+ Added an import file progress dialog
* Refactored SamplesDataFile

I refectored it to have a defined construction order in global space,
I'm going to make it private to Application soon, this is an
intermediate step.
* Refactored-SamplesDataFile now private again

Made SamplesDataFile a private member of Application, it wasn't
intuitive as a member of the manager that managed it.
* Began refactoring TapesDataFile to match

Moving TapesDataFile to be a private member of Application, and using
callbacks instead of direct access to it.
* Fixed-Tapes can be renamed again
* Refactored sample instance

Sample instances are now added through the tape manager, to permit
callbacks
* Small refactor with Sample Guid parameter
* Fixed SampleInstance deletion not saved