Remove vendored Qcircuit.tex
Remove vendored Qcircuit.tex

This file included GPL'd code, which is incompatible with QuTiP's
3-clause BSD licence.  Instead, we rely on the user to have a functional
install of the file (it's been included in TeXLive since at least 2014).

This also attempts to maintain patches made to the LaTeX code.

See qutip/qutip#1579

qutip/qutip,qutip/qutip,cgranade/qutip,cgranade/qutip