Add Si1442DH

Add power mosfet Si1442DH

Datasheet: http://www.vishay.com/docs/63772/si1442dh.pdf

• Provide a URL to a datasheet for the symbol(s) you are contributing
• An example screenshot image is very helpful
• Ensure that the associated footprints match the official footprint library
• If there are matching footprint PRs, provide link(s) as appropriate
• Check the output of the Travis automated check scripts - fix any errors as required