hgweb: replace .sourcelast with .bottomline that does the same...
hgweb: replace .sourcelast with .bottomline that does the same
In paper and Coal, basically, div.sourcelast was only used to make a 1px border
on the bottom of file source view (and only there). It's better to use
bottomline class, that also exists for the same purpose (visually), but is used
more widely and works without needing an empty <div>.
