better handling for absorption matrix array
add warning, increase integral accuracy from 1E-6 to 1E-7 (tau=3, forward=0.01, alpha=0.00376783, beta=0.2, nu=0.01, rho=0.75 has a discontinuity in the call price function with 1E-6 around atm), avoid exception in GaussLobattoIntegral when the density is zero in the integration domain, add constant for density lower bound computation, add inspector for model implied forward, add fall back to smile section if implied vol can not be computed, amend test case due to changed integral accuracy
update description