[Cin] Plugins in integer or in float

[Andrea paz]

> do you have simple test file we can load, add plugin in rgba_float), output and easily see that it clipped?
It would take an HDR image, however without an HDR screen we would
always see the clip. To see the content beyond the clip one would have
to do tone mapping (e.g. divide all values by 2 so that even those
above the 0-1.0 range would come back within the range and then we
could see details where we had burning whites before). I will try some
tests tomorrow. If histogram does clip, the tone mapping should not
work, and instead of burning whites a gray with no detail should
appear. If it uses floats the details should appear.