renamed BaseCallGraphCommand to BaseMethodCommand
traversal of vertex not contained in graph must not throw exception but
return fast
removed unused create methods
added missing precondition checks
Merge branch 'master' into feature/supportTypeUsageGraph
added command "used" which displays class dependency graph top down
converted base class BaseMethodCommand to a more generic class for all
commands which use the CallGraph model
removed duplicated output of "[M]"
changed ShowUsedGraph command to use new base class for graph commands