Towards an implementation of sBranch
Some code shuffling..

The goal is to get rid of the false dependency of Prover.hs on Model.hs
more code movement to break dependencies further
more code movement

trying to reduce dependencies
Introduce sBranchTimeOut

User-controlled time-out in sBranch calls
Use explicit sBranch extractor
A first implementation of sBranch

not quite functional yet
More work on sBranch

still not operational..
Add sBranch to notes