[datatable-help] v1.7.2 now on CRAN

[Matthew Dowle]

NEW FEATURES

o  unique and duplicated methods now work on unkeyed tables (comparing
   all columns in that case) and both now respect machine tolerance for
   double precision columns, implementing FR#1626 and fixing bug #1632.
   Their help page has been updated accordingly with detailed examples.
   Thanks to questions by Iterator and comments by Allan Engelhardt on
   Stack Overflow.
        
o  A new method as.data.table.list has been added, since passing a
   (pure) list to data.table() now creates a single list column.


BUG FIXES

o  Assigning to a column variable using <- or = in j now
   works (creating a local copy within j), rather than
   persisting from group to group and sometimes causing a crash.
   Non column variables still persist from group to group; e.g.,
   a group counter. This fixes the remainder of #1624 thanks to
   Steve Lianoglou for reporting.
        
o  A crash bug is fixed when j returns a (strictly) NULL column next
   to a non-empty column, #1633. This case was anticipated and coded
   for but an errant LENGTH() should have been length(). Thanks
   to Dennis Murphy for reporting.
        
o  The first column of data.table() can now be a list column, fixing
   #1640. Thanks to Stavros Macrakis for reporting.