HoTCoffeeh: Hanbury Brown-Twiss correlation functions and radii from event-by-event hydrodynamics

$\textbf{HoTCoffeeh}$ ($\textbf{H}$anbury Br$\textbf{o}$wn-$\textbf{T}$wiss $\textbf{Co}$rrelation $\textbf{f}$unctions and radii $\textbf{f}$rom $\textbf{e}$vent-by-$\textbf{e}$vent $\textbf{h}$ydrodynamics) is a new computational tool which determines Hanbury Brown-Twiss (HBT) charged pion ($\pi^+$) correlation functions and radii for event-by-event (EBE) hydrodynamics with fluctuating initial conditions in terms of Cooper-Frye integrals, including resonance decay contributions. In this paper, we review the basic formalism for computing the HBT correlation functions and radii with resonance decay contributions included, and discuss our implementation of this formalism in the form of HoTCoffeeh. This tool may be easily integrated with other numerical packages for the purpose of simulating the evolution of heavy-ion collisions and thereby extracting predictions for heavy-ion observables.