yaml file parser requires col, row entries

Ndscope version 0.12.1 permitted yaml files which do not have col, row entries if there is just one plot. 0.14.1 requires these lines, even if there is only one plot and so there are just the lines col=0, row=0.

If either or both of these lines are missing, 14.1 onwards gives the error: raise ValueError("Template layout must specify a plot at row=0, col=0")