WyCS: Added another failing test case.
This test case is failing, apparently because quantifier instantiation
is not being triggered.  I'm not sure how this is possible!?
Apparently, it's to do with the sign instantiation trick
WyCS: Removed sign optimisation from Solver.
The sign optimisation was used to limit quantifier instantation to
situations which only gave rise to resolution.  However, this
optimisation does appear to cut out some good use cases as well, hence
I've reverted it for now.
Merge branch 'devel-wyautl' of github.com:Whiley/WhileyCompiler into devel-wyautl
WyRL: added RandomisedStateRuleRewriteStrategy.
This file was created a while ago, but I forgot to check it in!