Port to Coq 8.5 beta 2.
The port makes the following notable changes: * The carrier types of separation algebras and integer environments are no longer in Set. Now they have a type at a fixed type level above Set. This both works better in 8.5 and makes the formalization more general. I have tried putting them at polymorphic type levels, but that increased the compilation time by an order of magnitude. * I am using a custom f_equal tactic written in Ltac to circumvent bug #4069. That bug has been fixed, so this custom tactic can be removed when the next beta of 8.5 is out.