Update visual-star-search.vim

Added
xnoremap <kMultiply> :<C-u>call <SID>VSetSearch('/')<CR>/<C-R>=@/<CR><CR>
so that "*" on numerical keyboard (keypad) works the same as Shift-8 "*".

See also
http://vimdoc.sourceforge.net/htmldoc/term.html#<kMultiply>