- further improvements of ode exporter:
    reaction parameters are only exported if they are local parameters
    don't export assignments multiple times
- throw an exception in case an error occurred during export
- isLocalParameter with index cannot be used when opening Copasi files, lookup with name succeeds
Improved math model to handle discontinuities introduced through functions
and to successfully compile during SBML import.
Fixed Bug 1909. If the notes start with an html element we assure that
head and title elements are present.