worked around a funny Matlab gotcha when using syms in functions

https://www.mathworks.com/matlabcentral/newsreader/view_thread/237730

The issue is still there, so I've noted it in help syms, the workaround is only in my assert
format autogenerated fcns in octave-style like others
typo in a test
legacy unit tests -> symfun.m
remove deprecated python_sympy_cmd
prefer python_cmd to evalpy in core stuff
matlab test fixes
missing equals signs in docs
fixes for matlab tests