Remove unsed functions from MergeFn

Prathmesh had added linearize functions. They are no longer used.
Merge branch 'master' of https://github.com/WaliDev/WALi-OpenNWA
Revert "Disable a ProgramBddContext test which is currently failing."

This reverts commit 9de01e56d683eaf105df156304c8d1d073037ea6.
The reason for failing test was out of date baseline.