Missing "last updated" datetime in cross-world view

[kotarou3]

Since the market board data is cached, it is helpful to know exactly how out of date it is.

I'm aware that in the individual server tabs, they already show a "last updated" datetime, but it is missing from the cross-world tabs.

Since each server's market board data are updated asynchronously from each other across the DC, obviously just a single datetime won't work. Some possible solutions include:

1. Just show latest and earliest dates: Simple, and works as long as the data is updated at approximately the same day or so of each other
2. Show latest and earliest date with some maximum cutoff. Servers that were updated beyond the cutoff have their entries greyed out: More complex change, but is able to prevent unreachable servers screwing up the market data. The exact cutoff duration will need some thought (90th percentile?)

I suggest going with (1) for now (with maybe a mouseover saying to check each individual server tabs for exact dates), and putting (2) on a wishlist for a rainy day