0.2.3 CardMgr changes

Here's a quick description of the loading feature of the Card Manager. Previously, the Card Manager would only let you clear a card if it was already loaded onto the unit. The idea being, if they clear the card accidentally then at least they can create a new one.

Knecht is worried that oddball cards from previous elections might end up out at the polling place. He doesn't want poll workers confused by the "Load/Reload" prompts, which they should never see. So, I have changed the behaviour so that cards can only be loaded as part of administrator setup. The unit will now prompts "Ready To Load Keys" after the "Reload Keys" is selected with the manager card. The user can then load keys until the unit is next turned off. Once turned off, the keys are locked with the cards that have been loaded. Free keys can no longer be selected once the keys are loaded. If an unknown card is inserted into a loaded unit, then the key number will change to "?" (ie, no key), the card identifier is displayed with a "Clear?" prompt. The user can then clear the card.