v6.7.0

Added consistency checker

Modified subprojects (since v6.6.6):
cfa/cfa-analysis
common/analysis
common/common
common/core
common/grammar
common/multi-tests
frontends/c-frontend
solver/graph-solver
solver/solver
solver/solver-javasmt
solver/solver-smtlib
solver/solver-z3
xcfa/c2xcfa
xcfa/cat
xcfa/llvm2xcfa
xcfa/xcfa
xcfa/xcfa-analysis
xcfa/xcfa-cli
xcfa/xcfa2chc
xsts/xsts
xsts/xsts-analysis