Start to fix a few issues with hybrid path:
 - MIS wasn't computed correctly, especially in the presence of scattering media
 - path through material weren't accounted for correctly
 - when multiple shadow rays were traced at once, if some finished earlier than others, the results would be broken

Jeanphi
Fixed an uninitialized variable in hybrid path tracing
Fixed a problem in hybrid rendering related to an uninitalized field and to discarded computation of DL when RR kick in
Fix a potential out of bounds array index in bidir.

Jeanphi
Reenable wavelength mutation in metropolis sampler.

Jeanphi
Update for v1.2 final.

Jenphi
Fix for issue #1320, out of bounds filter LUT indexing.

Jeanphi
Remove the queue messagebox wanting a haltcondition, it was introduced
before queue-refactor and is now obsolete and confusing
Fixed MagnitudeReduce/MagnitudePrefix to handle negative numbers.
Fixed issue where hybrid renderer would enter an invalid state when loading scenes with incompatible light strategy.

If the check for compatible light strategy fails, the hybrid renderer is still in the RUN state, but is not actually rendering.

Due to being in the RUN state, additional rendering threads may be added by the user (luxrender/luxconsole). Since the renderer isn't really in the running state, this causes issues.
Allow loading of queue files with arbitrary extension from the commandline and fix a few messages for Apple.

Jeanphi
Merge
Added tag v12 for changeset ee0b9ff73d62
Prevent the imaging split view going over a useful (500px) margin
Support for the shadowraycount parameter in bidir.
This is an integer that define the number of shadow rays to be shot for each sampled light in next event estimation.

Jeanphi
Add a lightraycount parameter to bidir.
This parameter defines the number of light paths to trace for each sampled light.

Jeanphi
Add write interval field to GUI
Change display interval label to icon
SLGRenderer: updated the code to works with new LuxRays file layout

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branch : slg_renderer
SLGRenderer: merge

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branch : slg_renderer
Updated copyright year information

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branch : slg_renderer