+ All Samples now have a Windows Guid

There's more platform specific code, this needs to have a Posix variant
implemented.
* Samples.xml root node is now <ytpking>

I moved the <samples> node into a parent node, to make the same
specification valid for sample and tape xml files.
* Moved xml functions into base class DataFile

These were reusable functions that the new TapesDataFile will need, so
I'm moving them up into the parent class.
+ Began adding Tape saving feature
+ Tapes now save the samples used.
+ Tapes now save the samples used
+ Tapes now save when a sample is deleted
* Fixed number attributes not being overrwritten
* Fixed changing tapes while playing breaking
* Fixed Timeline able to play when empty