Function: lfunorderzero
Section: l_functions
C-Name: lfunorderzero
Prototype: lGb
Help: lfunorderzero(L): computes the order of the possible zero
 of the L-function at the center k/2 of the critical strip.
Doc: Computes the order of the possible zero of the $L$-function at the
 center $k/2$ of the critical strip; return $0$ if $L(k/2)$ does not vanish.
