Changes in xts 0.7-0:

o  A new NEWS file.  

o  print.xts now passes ...

o  endpoints speedup and bug fix (thanks Ismail Onur Filiz)  

o  na.omit bug on logical and NaN fixes (thanks Fabrizio Pollastri
   and Koert Kuipers)

o  fromLast=FALSE for na.locf.xts.  Matching to zoo. (thanks
   to Sandor Benczik)

o  LGLSXP support in leadingNA (R fun naCheck)

o  fixed logical and NA 'j' subsetting. Thanks Koert Kuipers.

o  as.xts and as.timeSeries fixes for timeSeries changes

o  merge and subset now support dimensionless xts (non-standard).
   merge segfault fixed when merging all 3 or more zero-width xts objects
   and only zero-width objects.  Thanks to Koert Kuipers for the report.

o  added which.i to [.xts to return i values found via
   ISO8601 subset string

o  new lines.xts and plot.xts, similar to methods in zoo

o  lastof now has sec to 10 microsecond precision, and subsec
   arg to append to secs.

o  xts() further consistency in NROW/index check

o  align.time error checks for positive n= values (thanks Brian Peterson)

o  toPeriod updates in C, almost exported. ~600-1200x faster

o  new lag_xts in C.  Increased speed and index flexibility.

o  endpoints 'days' bug fix 

o  .makeISO8601 function to create ISO8601 compliant string
   from xts objects