mllib: Rewrite text wrapping function so it can handle newlines within the text.
Use -v and -x flags consistently across OCaml virt-* tools.

virt-customize:
virt-sparsify:
virt-sysprep:
virt-v2v:
  - These tools consistently used -v to mean verbose/debugging
    and -x to mean enable libguestfs tracing.

virt-builder:
virt-resize:
  - These two tools did not recognize -x at all, and used -v
    to enable libguestfs tracing and general debugging.
  - This commit changes these two tools to consume -v/-x
    consistently with the other tools.

Unfortunately this has a cascade of effects through the code.
v2v: Modify conversion step to first do proper inspection and data
gathering about the guest.