Fixed slicing of nodes with multiple outputs
Fixed substitution of variables by definitions in quantifier elimination
Add k-true properties as invariants in BMC
Choose last node when main annotation is missing
Change option to --timeout_wall and --timeout_virtual
Warn if list of properties is empty
Add property to node if subrange cannot be type-checked
Split predicate definitions to initial state constraint and transition relation
Merge pull request #84 from chsticksel/master

Bugfixes and minor refactoring