Changes:
* New API calls iso_write_opts_set_part_type_guid(),
iso_write_opts_set_iso_type_guid()
* New API call iso_nowtime()
* New flag bit2 of iso_node_set_acl_text() to be verbous about failures
* Made libisofs ready for building out-of-source. Thanks Ross Burton.
* Bug fix: Appended GPT partitions were not covered by the protective MBR
partition
* Bug fix: Multi-session emulation spoiled GPT production.
"GPT partitions ... overlap". Regression towards 1.4.8
* Bug fix: Appending partitions 5 to 8 caused damaged ISO filesystems if not
for SUN disk label
* Bug fix: SIGSEGV happened if options bit 14 of
iso_write_opts_set_system_area() is set and no El Torito boot image
is defined