Several typos and uniformity fixes.
Note:
*SCL/SimpleDataTypes.py is a upstream stepcode file whose fiz has been submitted upstream and accepted.
*the header of Tools/generateBase/generateMetaModel_Module.xsd had redundant data. It has been removed. Please double check it.
+ some are doxy others are just comment code.
+ some minor whitespace and grammatical tweaks.
+ app/SCL/* typos have also been submitted upstream (https://github.com/stepcode/stepcode/pull/366). So it's ok to merge them in to master.