plugin loading should use dlopen(...,RTLD_LOCAL)

from the dlopen man page:
RTLD_LOCAL: Symbols defined in this library are not made available to
resolve references in subsequently loaded libraries.
update gitattributes
update gitattributes
group all plugin IDs in EffectInstance.h
Image: allow infinity values for now
OfxEffectInstance: tuttlegamma goes to Color/Math
update openfx
Node creation dialog: bug fix, don’t compare against the group name
OutputThreadScheduler: don’t allow in the buffer more than 3 *
maxHardwareThreadCount.
OutputSchedulerThread: make sure to pass inputImages to renderRoI so
they don’t get re-rendered
update openfx
Implement groups gui
Merge branch 'python' into workshop

Conflicts:
	Engine/AppInstance.cpp
	Engine/ProjectPrivate.cpp
	Gui/NodeGraph.cpp
	libs/OpenFX
Revert "Merge branch 'python' into workshop"

Conflicts:
	Engine/AppInstance.cpp
	Engine/ProjectPrivate.cpp
	Gui/NodeGraph.cpp
	libs/OpenFX
Merge workshop into python
Merge branch 'workshop' (early part) into python
Merge branch 'workshop' into python