Philipp Krüger authored Nov 21, 2019 and Marge Bot committed Nov 28, 2019

* Transformed the type aliases `InterestingCxt`, `InsideLam` and `OneBranch`
  into data types.
* Added Semigroup and Monoid instances for use in orOccInfo in OccurAnal.hs
* Simplified some usage sites by using pattern matching instead of boolean algebra.

Metric Increase:
    T12150

This increase was on a Mac-build of exactly 1%. This commit does *not* re-intruduce
the asymptotic memory usage described in T12150.