Add Light Conversion

OK it would be nice if the app would also conver Lumes to watts for help comparing LED, incandescent, Fluorescent. When you are shopping it would be nice to be able to compare bulds, and if wanted a certain amount of Lumes with mutiple bulds it could help with conversion....etc.

Pretty simple but a big help when you or you wife is Home Depot trying to pick out bulbs.

alonghorn about Converter (unit conversions), v2.7.1