This commit introduces a generic partition creation interface which should be future-proof and extensible, and partially replaces the old sfdisk-based interface. The implementation is based on parted but is hopefully not too dependent on the particulars of parted. The following new calls are introduced: guestfs_part_init: Initialize a disk with a partition table. Unlike the sfdisk- based interface, we also support GPT and other partition types, which is essential to scale to devices larger than 2TB. guestfs_part_add: Add a partition to an existing disk. guestfs_part_disk: Convenience function which combines part_init & part_add, creating a single partition that covers the whole disk. guestfs_part_set_bootable: guestfs_part_set_name: Set various aspects of existing partitions. guestfs_part_list: List partitions on a device. This returns a programming-friendly list of partition structs (in contrast to sfdisk-l which cannot be parsed). guestfs_part_get_parttype: Return the partition table type, eg. "msdos" or "gpt". The following calls are planned, but not added currently: guestfs_part_get_bootable guestfs_part_get_name guestfs_part_set_type guestfs_part_get_type