Some work on the new bximage utility
- added support to resize images (currently supported: flat, growing and sparse)
- added image file name check and renaming if necessary
- set minimum hard disk size to 10 MB
- vmware4: make header structure available for usage in bximage


git-svn-id: svn://svn.code.sf.net/p/bochs/code/trunk@11894 6c8e4198-a580-4521-a02f-c9ae86df1db9