Implemented List container based on QList, with many enhancements

The similarities and differences are briefly outlined in TimedText/List.h.

They include:

 - No exceptions
 - Hidden/PIMPL'd private data.
 - No public unsafe operations
 - No assertions
 - STL-styled iterators (currently without iterator tags)

I've only implemented a very simple test suite, which conducts a
series of tests on primitive types. I'll be extending this as time
goes on.