Unblinded outputs greater than 21 million.

Any unblinded output (including fee outputs) is currently limited to MAX_MONEY (21 million) for any issued asset. 

To enable issued asset outputs greater than MAX_MONEY the MoneyRange checks in VerifyAmounts and CheckTransaction must be changed to only apply to policyAsset (pegged asset). 

This is a hardforking change, and also requires a handling for int64_t overflow in CheckTransaction. 