First stab at a new express parser to have some more luck with Ifc4

src/ifcexpressparser/README.txt

@@ -0,0 +1,9 @@
+This folder contains Python code to generate C++ type information based on an
+Express schema. In particular is has only been tested using recent version of
+the IFC schema and will most likely fail on any other Express schema.
+
+The code can be invoked in the following way and results in two header files
+and a single implementation file named according to the schema name in the 
+Express file. A python 3 interpreter with the pyparsing library is required.
+
+$ python bootstrap.py express.bnf > express_parser.py && python express_parser.py IFC2X3_TC1.exp