Removed 'delete' (-d) option and added new 'backup' (-b) option.
In convert/resize mode a backup can be created if the new file name
is not specified or the same as the source file name. In commit mode
both base image and redolog file are affected by the backup switch.
Added Linux specific file copy code using '/bin/cp'.


git-svn-id: svn://svn.code.sf.net/p/bochs/code/trunk@11920 6c8e4198-a580-4521-a02f-c9ae86df1db9