Consider how the multiwallet might help employ protections around network upgrades

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We have found cases where the wallet will naïvely attempt to perform transactions against the API when it might be better for the wallet to alert the user to wait until after the upgrade has completed. This may be doable in cases where we know the blockheight or the date of the network change and can be programmed into the multiwallet ahead of schedule.

In the case of BCH and ZEC (and eventually ETH) which have planned network updates, this is something we might want to consider for our client. This issue will serve to track that ongoing discussion, with the following goals:

1. What steps can the client take to protect the user during planned network upgrades?
2. Are there steps we can take to protect the user during unplanned network upgrades?

Additional Information/context:

1. Recommendations for ZEC
2. Specs for BCH upgrades (canonical?)