- Fix Bit8u instead of char weirdness for imageDisk (dreamer_)
- Give device_t a virtual empty destructor so some warning program
doesn't go crazy.
- Give the code that moves the Z drive its own function for readability.
- Give sizes arrays default values again for warning program.
- Rewrite IMGMOUNT in order to exit early for clarity and attempt
to group things together.
Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@4267
