Revert r54058, caused crash when adding paritcles in particle edit mode

MEM_recallocN() doesn't allocate memory when used on a null pointer.

Just revert commit since there is no real benefit to using
MEM_recallocN() in this case.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54108 954f8c5b-7b00-dc11-b283-0030488c597c
Check for deletion before moving vert in dyntopo collapse edge

Fixes [#33964] Dyntopo crash with edge collapse + undo
projects.blender.org/tracker/?func=detail&aid=33964&group_id=9&atid=498

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54109 954f8c5b-7b00-dc11-b283-0030488c597c
Fix [#34005] blender will close immediately in debug mode on deleting objects

Was silly mistake from rigidbody merge, base was used after it's been
freed.

Now don't free base in BKE_scene_base_remove() and rename it to
BKE_scene_base_unlink().

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54110 954f8c5b-7b00-dc11-b283-0030488c597c