Implemented 'light near start' for EDFs
Fixed leftover cosine term, reference images.

        - Fixed left-over cosine term in final accumulator expression.
        - Re-rendered reference images, updated test scenes.
Fixed 'light near start' for sppm and lighttracing
fix issue #316
Fixed PR comments
Merge pull request #407 from camargo/master

Fixed issue #316: Print a warning when doing multipass rendering but pixel decorrelation is off
Merge pull request #400 from vidarn/master

Implemented 'light near start' for EDFs
small code tweaks.
emit a warning if an EDF's light near start value is negative.
code tweaks.
remove render widgets before loading a project file.
tweaked Qt object names.
removed unused style.
small style tweaks.
Fixed imath library names for external linking.
Fixed imath library names for external linking.
Merge pull request #414 from est77/master

Fixed Imath cmake library names on linux.
tweaked formatting.
minor code tweak.
Fixed potential negative pdf values.

        - Fixed potential negative pdf values when evaluating the BRDF
          response, one of the cos(phi_diff) factors was not absolute.