ds.plink useds first row for results as header

[StuartWheater]

If the results obtained by ds.plink from the plink command does not contain a header the first line of the results will be used as the column headers.

[ESCRI11]

Hello @StuartWheater , can you provide some reproducible code so I can look into this and #22 issue? I have some ideas about solving both issues, on the issue #22 you said you are investigating about them... would you like me to look into them or I should expect a pull request from you side in the near future?

[StuartWheater]

Hi, I will work on creating a reproducible example which can be run on opal-demo.obiba.org. I have a workaround for the issues, but I have't worked up the changes to pull request.

I will keep this pull request separate from the one supporting returning multiple results, Shell Resource support and ds.plink_assign