Loading Stella models - some issues

[erikvullings]

Hi Bobby!

I've been working with processing some Stella stmx files from one of my colleagues, and ran into the following issues:

• The model contained an empty group, which caused an XML deserialization error ('missing field $value'). Annoyingly, it does not display the line number, so it was hard to find.
• The model contained variables like Self-management. In equations, this becomes "Self-management" (so it will not mistake the - for a subtraction), which caused errors as these variables could not be found. I renamed them all manually.
• External data using a connector cannot be processed, and cause errors of unknown dependency.
• The model contains a SMTH3 function. Is this actually implemented in the code, or do you use a delay for that?
• Units such as days/week are acceptable, but not units such as days per week. Not sure if Stella does support them, though.