colorout: hide/unhide rendering intent controls according to preferences

this hides or unhides the rendering intent controls after each run of
pixelpipe if needed. there is still no immediate reaction on a change of
the lcms2 configuration parameter; at least the GUI now updates faster
than before.
Workaround for libgphoto2 API breakage in 2.5.0. Fixes red hat bug #892228.

Thanks to jpopelka for debugging and proposed patch. :-)

Signed-off-by: Christian Tellefsen <chris-git@tellefsen.net>
white balance: make it relative to daylight balance

assuming that has been created wrt CIE daylight.

the end result is somewhat similar to ufraw, numbers vary wildly
but in principle it's relative to something constant and not to
camera white balance anymore.

also removed second temperature slider.

Conflicts:
	src/iop/temperature.c

Probably related to a6210a75453d5729a6c4efa50ec8eb0decd2097d