remove mentions of natron.fr

jenkins: better options

changelog update

Merge branch 'RB-2.3' of https://github.com/NatronGitHub/Natron into …

…RB-2.3

cangelog: update

changelog

ViewerInstance: do not take write lock at each render

update doc

fix build

AppManager: cache can be restored even if running in background (why …

…not?)