preliminary DPLL(T) implementation done, all but one compile error fixed
changed handling of literal ids. more general now, shouldn't be a big influence on performance and is extensible. does not compile, because change to propositional skeleton necessary in order to tell theory and propositional literals apart
test6 passing with Unsat result, but matcherror with rest
no subclassing of literals anymore, literal ids are now computed depending on a
field every time they are accessed. tests are running, but due to the id changes
can't be run in parallel by sbt anymore (which is disabled in build.sbt)