Added a new Bio-PEPA test in the form of the familiar MM example model. Also removed our homebaked assertAlmostEqual as I now realise that this is included in the unittest library.
Updated the expression parser to use the operatorPrecedence function of pyparsing rather than doing all of the parsing ourselves. This means that it was also trivial to add the power ** operator and I've added a test for that to the TestConstantDefinitions test
Added a test for including rate constant definitions in PEPA models as they are in Bio-PEPA models, but not yet implemented that so the test is failing
Made the BioRateConstant into the more generic sounding ConstantDefinition ready for use in PEPA models as well
There actually was a parse error in the model source for TestApparentRateWithConstantDefs
Added rate constant definitions to PEPA models. Quite happy with how that is working now. One could define a reasonable PEPA model using this, though I have not yet included TOP as a rate.