* Disk space warning if the recording potentially will not fit in disk space available.
* ProgressDialog enhancements that allow the Stop/Cancel button to be confirmed and the elapsed time to be hidden.
* Messages enhanced to clearly show the actions being taken.
... Should have no effect on generated code, except perhaps some slight faster
virtual function calls. Mostly useful as documentation of design intent.
Tried to mark every one of our classes that inherits from another, or is a
base for others, or has abstract virtual functions, and a few others besides.
