Some work on the new bximage utility
- added support to use 'concat' and 'dll' mode images as convert source.
  A prefix ("concat:" or "dll:") must be added to the path since autodetection
  doesn't work for these modes.
- create: fixed virtual disk size calculation based on C/H/S
- convert / resize (interactive mode): use original filename as the template for
  the new one if not specified on the command line


git-svn-id: svn://svn.code.sf.net/p/bochs/code/trunk@11911 6c8e4198-a580-4521-a02f-c9ae86df1db9