AttitudesSequence does not manage backward propagation consistently
It is possible to use AttitudesSequence with backward propagation, but
it is quite difficult.
When calling addSwitchingCondition, the user has to revert the before/after attitude providers,
but should not reverse the switchOnIncrease and switchOnDecrease flags.
The API should better be made consistent with events detection (and in
particular with the
increasing flag), i.e. everything should be defined as if propagation were forward, and internally
the implementation should adjust itself for backward propagation. This way, the same natural
definition is used regardless of the propagation direction, and once a sequence is defined, it
doesn't need to be modified if the user navigates back and forth in time when performing search
(from redmine: issue id 206, created on 2015-06-04, closed on 2016-02-10)