[Bf-codereview] Compositor debug improvements (issue 13699043)

[lukas.toenne at gmail.com]

Reviewers: bf-codereview_blender.org,

Description:
Cleanup and improvements of the compositor debug output.

Debug code for graphviz output moved to a dedicated file
COM_Debug.h/cpp.

The DebugInfo class has only static functions, which are called from a
number of places to keep track of what is happening in the compositor.
If debugging is disabled these are just inline stubs, so we don't need
#ifdefs everywhere and don't get any overhead.

The graphviz output is much more useful now. It uses a number of colors
for various special operation classes. ExecutionGroups are indicated in
graphviz with clusters.

Currently the graphviz .dot files are stored in the BLI_temporary_dir()
folder. A separate dot file is generated for each stage of the
ExecutionGroup scheduling, this is intended to give some idea of the
compositor progress, but could still be improved.

Please review this at https://codereview.appspot.com/13699043/

Affected files (+524, -162 lines):
   source/blender/compositor/CMakeLists.txt
   source/blender/compositor/intern/COM_Debug.cpp
   source/blender/compositor/intern/COM_Debug.h
   source/blender/compositor/intern/COM_ExecutionGroup.cpp
   source/blender/compositor/intern/COM_ExecutionGroup.h
   source/blender/compositor/intern/COM_ExecutionSystem.cpp
   source/blender/compositor/intern/COM_ExecutionSystemHelper.cpp
   source/blender/compositor/intern/COM_ExecutionSystemHelper.h
   source/blender/compositor/intern/COM_NodeBase.h
   source/blender/compositor/intern/COM_NodeOperation.h
   source/blender/compositor/operations/COM_SetColorOperation.h
   source/blender/compositor/operations/COM_SetValueOperation.h
   source/blender/compositor/operations/COM_SetVectorOperation.h
   source/blender/compositor/operations/COM_TrackPositionOperation.h