Changed the location of theta in n_pendulum_on_cart
Changed the location of theta in n_pendulum_on_cart

The theta variables now represents the angle between the vertical y axis
and the pendulum axis.

rahuldan/sympy,souravsingh/sympy,aktech/sympy,souravsingh/sympy,postvakje/sympy,madan96/sympy,chaffra/sympy,souravsingh/sympy,drufat/sympy,postvakje/sympy,ChristinaZografou/sympy,sampadsaha5/sympy,sampadsaha5/sympy,hargup/sympy,postvakje/sympy,drufat/sympy,chaffra/sympy,jaimahajan1997/sympy,madan96/sympy,kaushik94/sympy,kaushik94/sympy,jaimahajan1997/sympy,skidzo/sympy,skidzo/sympy,kaushik94/sympy,yashsharan/sympy,drufat/sympy,yashsharan/sympy,aktech/sympy,skidzo/sympy,hargup/sympy,aktech/sympy,madan96/sympy,ChristinaZografou/sympy,rahuldan/sympy,sampadsaha5/sympy,hargup/sympy,jaimahajan1997/sympy,ChristinaZografou/sympy,chaffra/sympy,rahuldan/sympy,yashsharan/sympy