- added more documentation.
- defined make-encumbered.
- changed lookup-implies-cxt2perm1 to clsmap-cxt-implies-ty2perm.
- moved can-duplicate-borrow and can-duplicate-shared from
  conversion.thm to this file.
- moved can-duplicate-borrow and can-duplicate-shared to
  conversion.elf.
- added more documentation
- only activate read and write for now. Rests are commented out.
- defined not-equal relation between effects, defined
- eq?, and proved eq?-total.
- changed clsmap-cxt to only allow borrowed and shared type in cxt.
- fixed leq-preserves-clsmap-cxt-tgtmap.
- efxmap2tgtmap-empty.
- previous revision is broken, now fixed.
- 2013-07-31.
mode change