Improve error checking for bar_from_space_type_ratios

[DavidGoldwasser]

• There is some flexibility on spacing, but a space is required after the comma to work, make that optiona.
• Support ratio that adds up to more than 1 by issuing warning and normalizing it
• Support ratio that adds up to less than 1 by issuing a warning and normalizing it.
• Support unrecognized space type names but issue warning that downstream measures like create_typical may not work as expected. I already support custom space types within a recognized building type, but not custom building types.