[Libguestfs] [PATCH v2] Add progress bars

This is an updated and extended version of the original patch: https://www.redhat.com/archives/libguestfs/2010-August/msg00163.html This adds OCaml and Perl bindings (both tested), support for progress bars in virt-resize, and adds progress notifications to a number of the simpler commands. Still to do is to add progress messages to more commands. There are still a few commands which would be fairly easy (eg. download and some t*-out commands). There are many others where implementing progress messages will be quite a lot more complex. Note: I have changed the default frequency of messages. They are now sent after two seconds, and every 1/3rd of a second thereafter. This makes the progress bars smoother and avoids aliasing effects when displaying time left in seconds. Note (2): All known comments about the previous patches have been incorporated. Rich.