Warn if default config doesn’t exist in OpenColorIO-Config.
 This might be because the user doesn’t have the bundled
OpenColorIO-Config folder or because he/she has moved it.
EffectInstance: be careful when cropping infinite RoDs
SpinBox: avoid over/underflows
Animation button never gets the focus
Merge branch 'workshop' of github.com:MrKepzie/Natron into workshop
fix focus policy of many GUI buttons
AnimationButton never gets focus

fixes
https://github.com/MrKepzie/Natron/commit/a97e013fb46e52abf5401c0f6b3fa9
3254677ff0
more focus fixes
Add focus support for left toolbar
more focus fixes
ComboBox: set focus once the menu has been closed
Merge branch 'workshop' of github.com:MrKepzie/Natron into workshop
Infos -> Info everywhere
Add an extract functionality to selected nodes: CTRL  + SHIFT+ X
Merge branch 'workshop' of github.com:MrKepzie/Natron into workshop
Properly refresh viewers in undo()
Slider: when holding CTRL range is zoomed by 10, when holding CTRL +
SHIFT range is zoomed by 100
Properly recenter widget
Properly send up events that are not caught be children, this way the
timeline can be moved by key strokes form anywhere and properties can
be escaped properly.
Limit number of parallel renders according to RAM availability to avoid
swapping