Links are now always enabled for blips
Previously, it was only enabled for blips if there is
no legend (config.print_layout = true)
Use xlink:href everywhere
Previously, blips used xlink:href, but text still used href.
xlink:href has actually been deprecated, but currently still
has better cross-platform support.
Links can now open in new tabs
Previously, links always opened in the existing tab. This adds
a new config: links_in_new_tabs. Setting that to true will
add a target="_blank" for all hrefs, causing the link to be
opened in a new tab. Setting config.links_in_new_tabs to false
or not including it at all retains the old behavior.
Includes changes from #73.