Import doesn't match state to country

There are a handful of state names that recur in multiple countries. For instance, there is a Maryland in the United States and Liberia. However, when importing a list of contacts that includes American Marylanders and Liberian Marylanders, the state IDs that are saved are the same--that of Maryland, United States.

The same problem happens when importing people in Boston, MA (Massachusetts), United States and Mutare, MA (Manicaland), Zimbabwe.

By all appearances, the data will generally look correct from within CiviCRM (because of the same names and/or abbreviations), but search doesn't work properly. Moreover, when you go to edit a contact with a mismatched state, the state select field will go back to the blank "- select -" option because the saved state ID isn't among those available for that country.

Incidentally, this is also what appears to be the only roadblock left for implementing counties fully--I'll post a patch (as a separate issue) in a minute of what's done so far. County names in the US repeat a lot from state to state, so this type of matching is essential.