Fix crash when trying to open ammo menu with current team hog gear = nil Also fixes crash in A Classic Fairytale, mission 2 when rightclicking at Brainiac intro sequence (#142)

Fix caption not updating if adding caption with same text but different color

Increase duck cost in Construction Mode to 40

bulk copy of latest physfs to our misc/libphysfs since this seems to fix an off-by-1 error reliably hit in readln read of 1 byte probably introduced in the addition of the buffered read. Whether this is excessive or whether libphysfs should even be maintained by us is another matter. But at least we shouldn't crash