[datatable-help] v1.7.5 submitted to CRAN

[Matthew Dowle]

BUG FIXES

o   merge()-ing a data.table where its key is not the first
    few columns in order now works correctly and without
    warning, fixing #1645. Thanks to Timothee Carayol for
    reporting.

o   Mixing nomatch=0 and mult="last" (or "first") now works,
    #1661. Thanks to Johann Hibschman for reporting.

o   Join Inherited Scope now respects nomatch=0, #1663. Thanks
    to Johann Hibschman for reporting.

o   by= could generate a keyed result table with invalid key;
    e.g., when by= expressions return NA, #1631. Thanks to
    Muhammad Waliji for reporting.
        
o   Adding a column to a data.table loaded from disk resulted
    in an error that truelength(DT)<length(DT).
        
o   CJ() bogus values and logical error fixed, #1689. Thanks to
    Damian Betebenner and Chris Neff for reporting.
        
o   j=list(.SD,newcol=...) now gives friendly error suggesting cbind
    or merge afterwards until := by group is implemented, rather than
    treating .SD as a list column, #1647. Thanks to a question by
    Christoph_J on Stack Overflow.
        

USER VISIBLE CHANGES

o   rbind now cross-refs colnames as data.frame does, rather 
    than always binding by column order, FR#1634. A warning is
    produced when the colnames are not in a consistent order.
    Thanks to Damian Betebenner for highlighting. rbind an
    unnamed list to bind columns by position.
        
o   The 'bysameorder' argument has been removed, as intended and
    warned in ?data.table.
        
o   New option datatable.allocwarn. See ?truelength.
      
NOTES

o   There are now 472 raw tests, plus S4 tests.