set a minimum width on the attribute editor dock widget.
Merge https://github.com/appleseedhq/appleseed
Merge pull request #337 from DaviesX/master

translucency should be a color, not a scalar
fixed bug in 2c0d047ec0e4e31061e441099d28911e6db72c75: wrong scaling by translucency factor.

minor code edits.
minor code cleanups.
reverted a2ac6285756bdc3073ddea410f9fb4e274c56d06.

Reverted a2ac6285756bdc3073ddea410f9fb4e274c56d06: delete widgets immediately in appleseed::studio::clear_layout(). The reason is that we often have signals in flight when we clear layouts (for instance when we rebuild the entity editor form when changing the model of a BSDF), so deleting widgets immediately is incorrect and leads to crashes.
Merge https://github.com/appleseedhq/appleseed
Add ability to assign materials to both sides of an object instance at once