v0.20.0: a longer first day, and people you can turn away

Straight from the Owner's play-test of v0.19.0: day one felt "tense and short handed", and somebody joining felt "like a relief but possibly a burden at some point".

• Day one has room to make a choice. One survivor used to get about five hours, which bought four boards on a house with six ways in — and nothing else at all. The first pair of hands is now worth more than each later one, so a lone survivor gets about seven hours: enough to spend the whole board stock and make a trip. The house is still not fully covered. That part is the point.
• Anyone you find asks to join, and you can say no. They used to walk in automatically. Now a screen shows what they can do and what they cost — the hours they'd add from tomorrow, what breakfast looks like with another mouth, and how much bigger tonight's wave gets — and you let them in or leave them where you found them.
• Breakfast is forecast before it happens. The day screen now says "Food 0 for 2 mouths — 2 go hungry at dawn, and tomorrow is 4 h shorter." The cost of a full house was always there, and measurably harsh, but it was paid out of sight.
• Longer days made runs drift from 11–13 nights to 14–16, so the wave now grows faster as a run goes on: one more zeke every two and a half nights instead of every five.