Only use addBSNoChk for simple bitsets
Insert a formula into a bitset without checking for a contradiction. The
former addBS performed a contradiction-check using MiscSolver.arrayNeg
which is a array of size 0 due to not being initialized.
For some reasons this bug only could be triggered when building with
oasis and not with the old Makefile, though arrayNeg being of size 0 in
This fixes #12.