proposal: rename CAP to max_supply

[Bernardo Ramos]

The ARC1 already uses the term "Initial Supply". So what about using "Max Supply" instead of "CAP"?

The _setCAP() function could be renamed to _setMaxSupply()

And the state variable from _cap to _max_supply or _maxSupply

[Bernardo Ramos]

And maybe also add a function to retrieve it:

function maxSupply()
  return _maxSupply:get() or bignum.number(0)
end