The INITIAL_SUPPLY macro is generally not useful, and there's no good
way to fulfill the promise it creates. By removing it, I can skip the
scaling on the genesis values. Now, if there is an allocation at
genesis, the supply is determined by that allocation. Otherwise, the
supply is GRAPHENE_MAX_SHARE_SUPPLY and it all belongs to
GRAPHENE_COMMITTEE_ACCOUNT.
Also, remove one of the redundant and confusing MAX_SUPPLY macros and
unify the usage to always be GRAPHENE_MAX_SHARE_SUPPLY.
