commit 3666cebaea471a5582146732e8e896a45c1bf4b6

general remarks
 - instead of repeatedly doing string comparisons for file system and
   partition table types, it might make sense to parse them once and then
   work with enumeration constants.  You can do the parsing with a table
   relating string constants to enumeration constants and then searching
   the table for a match.  But it's not that big of a deal.
 - remember to eventually add your name and the current year to the
   copyright headers.  It's your code, so you get the copyright!

diskmenu.c

 - indentation error in if-statement.  Try an indentation like this:

		if (strcmp(part_to_copy->name, "") != 0) {
			asprintf(__DECONST(char ** , &bsditems[i].bottomdesc),
			    "Partition to copy: %s", part_to_copy->name);
		} else {
			bsditems[i].bottomdesc = "";
		}

filesystem.c
 - this code will be much less complicated if you write yourself a helper
   function that takes an array of pairs of bsddialog_menu_items and
   strings and then builds the radiolist, shows it to the user, and builds
   the commands from it.
 - doing so would also allow you to arrange the code such that the stuff
   is grouped by filesystem instead of by control flow, which would make it
   easier to add a new file system to the code.

gpart_ops.c
 - the BSD partition type is a "BSD disklabel"
 - the MBR partition type is a "MBR partition table".  I'm not sure what
   "DOS Partitions" refers to, as you can have other partitions than DOS
   partitions on an MBR partition table".  I would also mention that this
   partition type is needed for legacy boot.

important file system creation options
 - for the volname options, it might be useful to handle these in a systematic
   manner, perhaps the same way future glabel support is handled

newfs
 -E              recommended for SSD devices
 -L volname
 -U              should be on by default
 -O type         needs not be supported (UFS1 hasn't been used in years)
 -j
 -l
 -t

newfs_msdos
 -L volname

mkfs.ext2 mkfs.ext3 mkfs.ext4 (from ports)
 - these should be treated as one option with a dropdown to select ext2/ext3/ext4
 -E discard	recommended for SSD devices
 -j             we don't support journalling, but it'll be useful on Linux
 -L volname

mkexfatfs
 -n volname

mkntfs
 -L label
 -f		should be on by default
 -C