audit: Proposal Can Be Updated Just Before Voting Starts

[Orland0x]

The author of a proposal is able to change the execution strategy and payload of their proposal up to the moment when voting starts. This could mean that voters inform themselves about the proposal, decide how they would like to vote, and then vote when the voting period begins. However, if the author of the proposal updates it just before the start of the voting period, the voters may not realize it. This is especially problematic if the duration of the voting period is short, or if there is an incentive to vote quickly (for example in the case of an emergency).

[pscott]

Decided to solve this one via a UI warning rather than at a protocol level