The SIAM document classes do not admit multiple \thanks commands for an
author nor a \thanks command followed by a \footnotemark command. This
imposes limitations on the way authors can present the institutions they
are affiliated with. The previous logic used an assignment problem in
which each author can present at most one institution via \thanks. This
can lead to unsolvable situations, notably a single author with two
affiliations. The new logic uses fake authors, if necessary, to
effectively allow an author to present arbitrarily many institutions
using multiple \thanks.

Close #38