Now a tez cent is 10_000L. All constants are now in the
Constants_repr module and expressed as multiples of one_cent.
Add new function Qty_repr.mul_exn to multiply `tez` by `int`
eg. `10 tez = Tez_repr.(mul_exn one 10)`
`10 cents = Tez_repr.(mul_exn one_cents 10)`
Remove `Tez.{to,of}_cents` and replace them with `Tez.{to,of}_mutez`.
Installation:
`./scripts/opam-pin.sh && opam install tezos-node tezos-client`
Upgrade installed packages after a `git pull` (opam2 only):
`./scripts/opam-upgrade.sh`
Remove and cleanup every from the opam repo:
`./scripts/opam-unpin.sh`
