FIX: issue #506 and #488 (Complex compiler crash)

These crashes are caused by corrupted internal memory states in Rebol2, due to past-end series. The past-end series are sometimes produces by the compiler internal processing (it relies on volative blocks references). This patch tries to cure the symptoms only, we can't do much more about it for now. Self-hosting Red is the right solution.
Merge branch 'master' of github.com:dockimbel/Red