stemplot addition

[DCoderUltra]

Adapted plot and dataPlot to produce the default matplotlib stem, seems to work when I manually implemented it in a project and the python code produced seems fine.

[DCoderUltra]

Results obtained from the manual implementation.

Code snippet:

onscreen $ figure
% addSubplot 2 1 1
% stem n h @@ [ o2 "markerfmt" "tab:blue", o2 "linefmt" "tab:blue", o2 "basefmt" " "]
% grid True
% addSubplot 2 1 2
% stem n i @@ [ o2 "markerfmt" "tab:orange", o2 "linefmt" "tab:orange", o2 "basefmt" " "]
% grid True