emulate structure of binary op constant evaluation for unary ops but for starters only for the unary minus
Merge branch 'master' into utke1-bugfix-test
reference output changes caused by constant folding now covering unary minus which implies that the respective expressions will be turned into literal constants and no longer need to be extracted into a cache variable
Merge commit 'bc647bd504e15c3c6ea1bb22823f3e57a1516443' into HEAD