Enhanced Speedstep in the ports tree

[Colin Percival]

  There are now two ports providing Enhanced Speedstep
support: sysutils/est, which is a kernel module providing
a sysctl interface, and sysutils/estctrl, which is a daemon
which automatically adjusts the cpu speed based on the cpu
load and power source (AC vs. battery; there are three
settings for each, namely "min", "adaptive", and "max").
  After receiving considerable feedback, I've made the
reporting of cpu speed changes optional and disabled by
default.

  Thanks to everyone who has helped test these.

Colin Percival