fixed#81
is.empty is using sapply to check all elements of the passed R object - which is really lame to be applied on a data.frame (with e.g. 10e6 rows) -- so this is a quick workaround to fix enourmous performance issue when we are calling rapport on a big data.frame, although IMHO it's not a normal behaviour for even is.blank
Merge pull request #82 from Rapporter/development

fix for #81 and lame performance issue