[subsurface] Added a preference for time format (#100)

[Linus Torvalds]

On Sun, Jan 15, 2012 at 10:14 AM, Joahnnes Larsen
<reply+i-2847051-81bc4ca6d6013ae09ea932c117a940673de75309-1024025 at reply.github.com>
wrote:
> Added a preference so that the users can changed the time format to
> a strftime format string of their own choosing. The preference has its
> own frame named "Time format (http://linux.die.net/man/3/strftime)"
> between the frame "Columns" and the font button.

We avoid things like strftime very much on purpose. See for example
commit 97f09f3ea815 ("don't use strftime() due to locale issues")
which removed the last strftime use we had, because the output ends up
varying too much and being outright insane (ie no weekday/month output
AT ALL for some people).

So you need to do this by hand for portability reasons.

                        Linus