manuelluis/jsrrdgraph — pull request #5 by pommi (2013-05-18 19:42:57+00:00)
Title: VDEF doesn't show up in the legend

The GPRINT of a VDEF doesn't have a format. For example:
> "GPRINT:avg:LAST:%5.1lf%s Last"
> "GPRINT:tot:%5.1lf%s Total\l"

It didn't show up in the legend. Firebug showed variable format isn't
undefined, but an empty string in case of VDEF. So just check for falsy.