Log Message:
(math/R-zoo) Updated 1.8.11 to 1.8.12

Changes in Version 1.8-12

  o The autoplot() method for "zoo" objects now uses ggplot() directly \ 
rather
    than the qplot() function which has been deprecated in recent versions of
    ggplot2.

  o Support start = NA and end = NA in addition to start = NULL and end = NULL
    for unspecified start and end time of a window() of a zoo series.

  o Remove unnecessary S3 method declarations for axis.yearmon/yearqtr as
    axis() is no S3 generic, only Axis() is (reported by Kurt Hornik).

  o The helper function index2char() now calls format() instead of as.character()
    for objects inheriting from class POSIXt.