put test data in string instead of external csv
put test data in string instead of external csv

The rendered html vignette linked from the wiki doesn't give reference to this vignette folder, thus reader may have difficulties in finding the external csv file.

Since the data is small, it can be written in string and read by fread. I think this way reader can copy the code and test by himself/herself easier.
Rdatatable/data.table,vlulla/data.table,jangorecki/data.table,jangorecki/data.table,jangorecki/data.table,Rdatatable/data.table,Rdatatable/data.table,jangorecki/data.table,Rdatatable/data.table,vlulla/data.table,vlulla/data.table,vlulla/data.table