Remove StorageTool from project
Add read-only support for HFE virtual diskettes (API breaking)

Redesign IDisk interface to provide a better abstraction for disks by
removing any assumptions on sector numbering and organization.  It can
now be used to represent disks with varying number of sectors per track,
varying sector sizes and sectory numbering.

Add new class HfeDisk representing HFE format virtual diskettes.

Changed the syntax for the DUMP command in DragonDosTools.  It now
requires the disk head to be stated explicitly.  Head and Track numbering
now start at 0.