Code hygene.  Clip trailing whitespace
In "never_latch" mode, don't clobber the boot disk
Consistent umount method.  Previously some unmounts weren't logged.
Obtain host-wide and guest-specific PV limits.  Just print them out for now.
Common functions for identifying decompressors, and for copying data around.  No limits imposed.
Shell out to `md5sum`.  It is far more efficient.
Improve debug logging
Code hygene from Pylint:

 * Tabs -> spaces
 * Correct indentation
 * Drop redundant semicolons
 * Drop unused imports
CA-92995, XSA-25 - Apply kernel and initrd size limits to data processed by eliloader
Temporarily enable full debugging while confirming the XSA-25 fix.  Remove in due course