Initial checkin of GC
All accesses to Environments now go through REnvironment, which will soon be renamed to Environment and the old Environments will be made private.
More progress on GC.
Partial implementation of mark region gc
Merge branch 'master' of github.com:jtalbot/riposte into speedy
Removed Boehm GC. All riposte data structures are now allocated on our own GC heap. That doesn't mean our GC actually works yet though...
Initial implementation of mark-region GC
Small changes to gc
Moving more code into GC supported stuff
Merge branch 'speedy'