* Be a little safer with total issuance.
* PairT instead of _Pair
* Remove rev causing upset
* Remove fees stuff.
* Fix build (including tests)
* Update runtime, bump version
* Fix
* Handle gas refunds properly.
* Rename identifier
ala #2025
* Address grumbles
* New not-quite-linear-typing API
* Slimmer API
* More linear-type test fixes
* Fix tests
* Tidy
* Fix some grumbles
* Keep unchecked functions private
* Remove another less-than-safe currency function and ensure that
contracts module can never create cash.
* Address a few grumbles and fix tests