Blender Git Loki

Some small modifications.
Absorption and Dispersion parameters now only visible when 'Ray Transp'
enabled. WardIso specular amount scale to match Blender output.
Updated halo spotlight 'samples' to use new yafray syntax.

Quick addition for access to another yafray feature:
When using HDR backgrounds for lighting ('SkyDome' of 'Full' GI methods),
it is currently not always possible to get smooth lighting results.
Especially HDR images with small lightsource can be very noisy,
because currently yafray still relies on brute force random sampling.
As a temporary simple solution (better options will be available in the
'next generation' yafray), yafray can do some processing on the
image to smooth out all (or most) noise.
Besides smooth lighting, this also has
the advantage that AA will have less work to do,
GI quality can be set to the lowest level and still get reasonably
good results. Disadvantage however is that shadow definition is lost.
To switch on this option, set the world image texture filter parameter
to any value greater than 1.0
When 'filter' is 1.0 or less, normal hdr sampling is done as before.

So, current fastest possible render settings for IBL:
set texture image filter parameter of the background image to any value
greater than 1.0, set GI to 'SkyDome' type, enable 'Cache',
(possibly enable 'NoBump' when scene uses lots of bumpmapping),
set 'Quality' menu to 'Use Blender AO settings',
make sure AO is enabled in blender World buttons and set there the number
of AO samples to 1.
Should at least be good enough for previews.