Offset animated value nodes when modified in non animated mode.

Until now, when user modify an animated value in non animation mode, one exception is raised and a stop dialog message prompts to the user. It makes needed to turn into animation mode to modify a value at a certain time. 

This branch changes that behavior and instead of prompt the blocking dialog it offsets the waypoints for the whole animation of the value being modified. 

The behavior is a default and would be great to be possible to turn on or off this behavior depending on user preferences. Maybe it could be good to turn this behavior off by default and instead of stop the user action with the blocking dialog. The dialog could offer some options:

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You're trying to modify an animated value in non animation mode, what do you want to do?:

+  Turn animation mode on (and perform the value change)
+  Keep animation mode off and offset one waypoint (if current time is on a waypoint)
+  Keep animation mode off and offset all waypoints

[ ] Remember this action

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The feature works only for integer, real, time, angle and vector values. The rest of types cannot be offset in a consistent way so are not handled by this new way and would react like in the old way.