Explicitly disallow lambda with starred args in sympy_tokenize
Explicitly disallow lambda with starred args in sympy_tokenize

Previously it was relying on the generated Lambda having invalid syntax, but
the syntax of the generated Lambda is valid in Python 3.5 (but
nonsensical). Instead, we detect and disallow this explicitly in the
tokenizer. This also allows us to give a better error message.

Titan-C/sympy,yashsharan/sympy,mafiya69/sympy,lindsayad/sympy,kaichogami/sympy,lindsayad/sympy,hargup/sympy,postvakje/sympy,yashsharan/sympy,kaichogami/sympy,chaffra/sympy,souravsingh/sympy,Titan-C/sympy,mafiya69/sympy,Titan-C/sympy,skidzo/sympy,mafiya69/sympy,jaimahajan1997/sympy,sampadsaha5/sympy,rahuldan/sympy,kaichogami/sympy,jerli/sympy,chaffra/sympy,skidzo/sympy,madan96/sympy,postvakje/sympy,drufat/sympy,sampadsaha5/sympy,skidzo/sympy,jaimahajan1997/sympy,kaushik94/sympy,madan96/sympy,ChristinaZografou/sympy,drufat/sympy,ChristinaZografou/sympy,hargup/sympy,aktech/sympy,lindsayad/sympy,yashsharan/sympy,jerli/sympy,hargup/sympy,souravsingh/sympy,madan96/sympy,kaushik94/sympy,drufat/sympy,chaffra/sympy,Curious72/sympy,rahuldan/sympy,Curious72/sympy,rahuldan/sympy,souravsingh/sympy,postvakje/sympy,jerli/sympy,ChristinaZografou/sympy,aktech/sympy,Curious72/sympy,kaushik94/sympy,sampadsaha5/sympy,aktech/sympy,jaimahajan1997/sympy