Fix getprotocolvotes switch dates

• when a protocol switch is going to be skipped because another bigger upgrade will happen earlier, the command displays a switch date that will never happen (https://discuss.nubits.com/t/b-c-exchange-5-0-1-release-upgrade-before-18-july/4279/40?u=sigmike)
• when a protocol has switched, it still checks for a switch date and finds one (which is of course incorrect) (https://discuss.nubits.com/t/b-c-exchange-5-0-1-release-upgrade-before-18-july/4279/36?u=sigmike)

To solve these two problems we should probably just detect all the protocol switches that are going to happen within the next 2 weeks (while applying the switches to the fake chain), and assign the dates to the switching protocols.