* Integrated miniSAT into cutIntroduction. improveSolution2 now calls miniSAT instead of the bottom-up LK prover to check for tautologies. It can be tested via cutIntro3 in the shell.
* Inserted debug-messages to provide performance information about improveSolution and improveSolution2.
* Deleted utils/ds/lists.scala and merged its one function into utils/dssupport/listSupport.scala

git-svn-id: http://gapt.googlecode.com/svn/trunk/source@1599 85d21ef8-add0-11de-ae77-5bfb9c5a3f34