touch(1): Reintroduce local changes

touch(1): Reintroduce local changes

Major changes introduced by the update from FreeBSD:

* Add the 'h' flag to operate on symlinks rather than what they point to.

* Add -A flag to adjust existing time stamps.

* Add the -d option from POSIX.1-2008.
  This is much like -t but with a different format which is ISO8601-like
  and allows fractions of a second.

* Remove the advertising clause from UCB copyrighted files. This
  is in accordance with the information provided at
  ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change

* Remove useless and potentially dangerous rw() function which tries to
update access and modification times by reading and writing the file.