Log Message:
Update to 1.7.12

Upstream changes:
Changes in Version 1.7-12

  o read.zoo with a data.frame argument now defaults to FUN = identity
    if the index.column is not character or factor.  See ?read.zoo for
    additional details.

  o Added a dim<- method that checks whether the new dimension value
    appears to be ok and then calls the default.

  o The index<- and time<- methods now enforce that the new time index
    is actually correctly ordered (suggested by Joshua Ulrich).

  o read.zoo() heuristic improved so that POSIXct rather than Date is
    detected in cases like: read.zoo(text = "2010-01-01 12:05:03 88.1",
    index = 1:2).

  o The fortify() method now has a col.names argument that allows to set
    (some of) the column names of the resulting data.frame.

  o Various small bug fixes and enhancements.