Add an option to silence console feedback

[gergondet]

As mentioned by @arntanguy in #250 we sometimes wish to silence feedback when adding large numbers of collisions.

There's other situations where the console output a lot of "noise". For example, while walking constant transitions messages about SingleSupport->DoubleSuport and contact state changes are useful while working on the walking controller itself but distracting in another context.

A simple approach is to:

• provide an option in contacts/collisions manipulations functions (and yaml counterpart) to disable console feedback
• provide a similar option for the FSM executor that would silence transition messages