Aston Martin has launched its first plug-in hybrid in the form of the Valhalla The Valhalla is a mid-engine supercar powered by a twin-turbo V-8 and trio of electric motors The Valhalla produces a combined 1,064 hp, or enough for 0-62 mph acceleration in 2.5 seconds Production will be limited at 999 units, each is rumored to cost about $1 million…