initial conversion of some files to conservative registration
Changed list stroage temp value registration.

Previously, temporary values registered during a recursion were added to a
std::list as VALUE and not VALUE*.  While this would keep the GC from
collecting them, this could cause problems because the address registered was
on the stack and might go out of scope.  Changed to store and register
VALUE*s to avoid this.
Merge branch 'master' into conservative_gc
additional conservative registration markings in dense

Also removed unneeded registrations from set.
Conservative registration for yale storage

Also removed some unnecessary registrations.
Merge branch 'list_regression' into conservative_gc

Conflicts:
	ext/nmatrix/storage/list/list.cpp
	ext/nmatrix/storage/list/list.h
Conservative registration in data.cpp
Change internal list storage temp object unregistration functions to static
Conservative registration for list storage

Also removed some unnecessary registrations.
Additional conservative registration marking

Also checked to make sure that NM_CONSERVATIVE was actually removing the
statements (turns out it wasn't) and made a modification so that this is
working correctly.
Merge pull request #170 from cjfuller/conservative_gc

Conservative gc registration