In principle, these double phases should work without problems,
but they issue the error

"qualBindTopEnv _#case6" failed in function "Env.Value.bindFun"

so further investigation is needed

Nonlinear patterns have to be desugared first to eliminate multiple occurrences
of the same variable outside the scope of a single functional pattern.
This commit changes the order of pattern desugaring in that desugaring of
nonlinear patterns is now performed first.
Consequently, functional patterns have to be considered when eliminating
nonlinear patterns and the implementation is adapted accordingly.