[Libguestfs] [PATCH INCOMPLETE 0/4] v2v: Add general mechanism for input and output options.

This patch isn't quite complete (see ‘assert false’). Currently we have a bunch of ad hoc options like --vddk* and --vdsm* (and proposed to add --rhv*) to handle extra parameters for input and output modes/transports. This complicates the command line parsing and also the clarity of the command line (becauseit's not very obvious which options apply to which side of the conversion). Replace these with a general mechanism for handling input and output options. Thus (for example): --vddk-thumbprint=... becomes -io vddk-thumbprint=... --vdsm-compat=0.10 -oo vdsm-compat=0.10 The responsibility for parsing input and output options moves into the input and output drivers. This improves error checking so it's harder now for wrong flags to be included on the command line when they don't apply to the current mode. The old option names are preserved for compatibility. Rich.