Remove dead code (edge_set and related functions).
Don't forget to decrement string references.
Remove all references to worker.
Add copy_runtime to vm::tuple.
Added copy method to rstring.
Remove assert_tuple.
Merge branch 'master' of github.com:flavioc/meld into flavio

Conflicts:
	db/node.cpp
	db/node.hpp
	runtime/list.hpp
	sched/base.cpp
	vm/tuple.hpp