Function: qfbhclassno
Section: number_theoretical
C-Name: hclassno
Prototype: G
Help: qfbhclassno(x): Hurwitz-Kronecker class number of x>0.
Doc: \idx{Hurwitz class number} of $x$, where
 $x$ is non-negative and congruent to 0 or 3 modulo 4. For $x > 5\cdot
 10^5$, we assume the GRH, and use \kbd{quadclassunit} with default
 parameters.
