Moved external packages into main dir

Signed-off-by: oleg komarov <o.komarov11@imperial.ac.uk>
Renamed (save)loadplotlycredentials into (save)loadcredentials

Signed-off-by: oleg komarov <o.komarov11@imperial.ac.uk>
Added all other relevant files for plot conversion

Signed-off-by: oleg komarov <o.komarov11@imperial.ac.uk>
Added overloaded plot method

Signed-off-by: oleg komarov <o.komarov11@imperial.ac.uk>