Add Gnuplot.pm

Add Gnuplot.pm along with Data.pm and unit test. Which is used as an
interface for gnuplot.

Signed-off-by: anton <haglundanton+github@gmail.com>
Misc bug fixes in Gnuplot.pm

Signed-off-by: anton <haglundanton+github@gmail.com>
Use random color in Graph.pm

Signed-off-by: anton <haglundanton+github@gmail.com>
Add pull in Git.pm

Signed-off-by: anton <haglundanton+github@gmail.com>
Add type to Graph.pm

Signed-off-by: anton <haglundanton+github@gmail.com>
Add last value to Graph.pm

Signed-off-by: anton <haglundanton+github@gmail.com>