Fix MathML conversion (#1086)
Fix MathML conversion (#1086)

SymPy's default MathML printer replaces underscores with subscripts,
resulting in a MathML formula unsupported by libSBML.

Co-authored-by: Fabian Fröhlich <644850cb8939d255ed752957b7c4458c52900f75@schaluck.com>
FFroehlich/AMICI,FFroehlich/AMICI,FFroehlich/AMICI,AMICI-developer/AMICI,AMICI-developer/AMICI,FFroehlich/AMICI,AMICI-developer/AMICI,AMICI-developer/AMICI