[phobos] Proposal of StopWatch module

[SHOO]

I made the module of the stopwatch, so I suggest it again here.

I suggested a time handling module that I called std.time before.
Unfortunately itself was not able to contribute to Phobos for the issue
of license. But, an important function was included in it. It is what is
the StopWatch suggested this time.

I have some knowledge about machine control engineering. In the field of
the machine control engineering, the high accuracy time measurement
often plays an important role.
For example, the case wants to perform the measurement of the voltage
with time by millisecond order for feedback control. When it looks like
it, resolution power is not enough by time acquisition such as C's time
function in many cases.

Or the high accuracy time measurement is important in the game
programming, too. Or in benchmark testing, too.

There is std.perf in Phobos as a module with this role now.
However, the module is unlisted, and a license doesn't seem to be a
Boost license, too.
I did not refer Tango at all about this class and examined and made it
in my own hand completely.

Here is the module to suggest this time:
    http://ideone.com/TVw1P

# This module is tested by Windows (real) and Ubuntu (virtual PC).

Please look at it once by all means, and review it.
I think that I will commit it at 2010-08-22T15:00Z as far as there is
not serious dissenting opinion.