func (ct *Ctr) Same() {
	ct.Chg = false
}
Same resets Chg = false -- good idea to call this on all counters at start of Step
or can put in an else statement, but that is more error-prone.
package env
type Ctr struct {
	Scale TimeScales `inactive:"+" desc:"the unit of time scale represented by this counter (just FYI)"`
	Cur   int        `desc:"current counter value"`
	Prv   int        `view:"-" desc:"previous counter value, prior to last Incr() call (init to -1)"`
	Chg   bool       `view:"-" desc:"did this change on the last Step() call or not?"`
	Max   int        `desc:"where relevant, this is a fixed maximum counter value, above which the counter will reset back to 0 -- only used if > 0"`
}
func (ct *Ctr) Init() {
	ct.Prv = -1
	ct.Cur = 0
	ct.Chg = false
}