zfsnap 2.0.0 - 2015-0?-??
  Version 2 is a major step forward for zfsnap. It aims to be the most usable,
  well-tested, and fastest version of zfsnap yet.

  Though some backwards incompatible syntax changes were made to the zfsnap command itself,
  the snapshot name format remains completely unchanged and backward compatible.

  Syntax Changes:
    - Renamed from zfSnap to zfsnap
    - Split functionality into two commands: `zfsnap destroy` and `zfsnap snapshot`
      - It is no longer possible to delete and create snapshots in the same call.
    - Merged "Pool Options" and "Generic Options"; they no longer need to be kept separate
    - '-e' flag  (return number of errors as return value) was dropped
    - '-zpool28fix' flag was dropped; it is now the default behavior
    - Numerous TTL tweaks (see TTL section)
  New Functionality:
    - `zfsnap recurseback`
      - to recursively rollback snapshots for a datset and its children
  Portability:
    - GNU/kFreeBSD now supported
    - Solaris-like systems no longer need GNU Utilities installed
    - OS X no longer needs GNU readlink
    - Fully POSIX compliant (except for use of "local" variables)
      - Should now run on any *nix that supports ZFS
  Performance:
    - Ported key functionality to pure sh, resulting in noticeable speedups
      - No more `sed`, `grep`, `readlink`, `dirname`, or `find` in code-base
    - Significantly decreased number of subshells spawned (hundreds -> a few)
  TTLs:
    - 'y' and 'm' are now *calendar* year and month (not 365 days and 30 days respectively)
      - See Manpage for more info
    - All TTLs are now validated
    - Integers supplied to '-a' without a TTL modifier are now considered invalid
      - No longer automatically converted into a TTL
    - New 'forever' TTL that will never expire
    - Leap years are now handled properly
  Future-proofing:
    - Unix time no longer used internally
      - Supports dates (and expiration dates) past 2038
  Reliability:
    - Wrote 250+ tests
    - Validates user input (like TTLs) and snapshot names better
    - Cross-OS and cross-shell testing
  License:
    - Relicensed from Beerware to BSD-3-Clause
  Random:
    - Bash and zsh completion
    - tcsh completion (only command and ZFS fs support; no flags)
    - Many bugs fixed and small features added