[Libguestfs] RHashtable and the python bindings

[Matthew Booth]

I've discovered that libguestfs apis which return RHashtable are
currently returned as a list of tuples in the python bindings rather
than the obvious dict. I propose fixing this, whilst also maintaining
API compatibility for a period of time.

The following apis return RHashtable:

inspect_get_mountpoints
list_filesystems
inspect_get_drive_mappings
tune2fs_l
mountpoints
md_detail
blkid
list_disk_labels

I propose the following:

h = guestfs.GuestFS(return_dict=True)

If return_dict is set, any RHashtable api would return a dict rather
than a list of tuples. If not, the behaviour would be unchanged. The
default would be False.

We would advertise immediately that this parameter is recommended for
all new code, and that old code should be updated. At some point in the
future the default would be changed to True, and at some point after
that the old code could be removed.

Matt