Have had helper functions in here for awhile but was working on the best way to implement.
I think it's best to preserve the existing SendXec function and simply load it with targetOutputs that match SLP spec. In this way, we can keep coinSelect simple --- it already expects targetOutputs as a param, so we should just calculate the proper targetOutputs for a given token tx and use it as normal.
Modify `getSlpGenesisTargetOutput` function to return to-spec target outputs for a fixed supply genesis tx. Implement in CreateTokenForm.js.
The resulting tx differs from the legacy tested tx only in having a better calculated fee.