Just some thoughts on what it would take to build one of these....
The timer, IMO, would be kind of iffy for me - I sit at lights for minutes waiting for a green arrow.
I do know that if I'm turning, I'm also squeezing the clutch lever a number of times. So, if I have my turn signals on, and I release my clutch lever twice, I'm probably done turning, and the signals should cancel.
For lane changing, the clutch activity would not apply - in that case, a timer would be better. So, if I'm traveling at a speed of greater than 8 MPH, and I flip on the turn signals, my signals should cancel in a number of seconds (30?).
These types of controls can be built with an embedded computer (Search for arduino). Detecting the clutch activity and determining if the blinkers are on is doable with voltage detection. Detecting if the Savage is moving is more difficult, as the speedo is mechanical. This would require putting sensor on the speedo cable (hall effect sensor), a bike speedo, or a GPS.
I use a couple of $3 buzzers from radio shack because that was easier