An extension is the string after the last occurence of a dot (.) in a path. This tool replaces extensions with other one.
Object describing which changes have to be made.
For instance {less: 'css', md: 'html'} means that the tool must replace extensions .less with .css and .md with .html.
var change = Matis.tools.ChangeExtension({less: 'css', md: 'html'});