killall - Add all-but-self tty kill (-T)

* Add a new feature to killall, the -T option, which will kill all
  processes on the caller's tty except processes which parent the
  killall.

  This can be used to terminate processes on the current tty, for example
  from a ^C'd build that failed to kill all the sub processes, without
  also taking out the shell/xterm/whatever and causing the window to close.
kernel: Update taskqueue subsystem

* Add taskqueue timeout functions

* Add _timeout_task_init()

* Add taskqueue_cancel()

Obtained-from: FreeBSD
drm2: add a drm_find_file_by_proc() implementation

* Taken from the existing drm code in sys/dev/drm/
kernel: Document new taskqueue functions
resolve mandoc(1) warnings in bin/
man4: use .Mt for emails (1/2)
man4: use .Mt for emails (2/2)

This concludes the efforts to consistently use .Mt for
email addresses.  It also sneaks in a couple of subtle
changes to punctuation, grammar and conversion of
'.Nm xxx' to '.Xr xxx 4' where appropriate.
kernel: Remove some unused kmalloc types in drm/drm2 code.

OK'd: ftigeot
revert changes to drm_memory.c and drmP.h