Engineers from Apple have applied for a patent on an “emergency” mode for cell phones that would squeeze every last drop of energy out of the batteries.The phone would recognize emergency calls when the user dialed an emergency number, such as 911 in the United States. But a number also could be stored as an “emergency number” on the phone (a spouse, child, parent, for example) or the user could manually put the phone in emergency mode.The process would do a variety of things. First off, it would disable “non-essential