Squashed commit of the following:

+ Fix for #5424. duplicated.data.table errors now for both by=TRUE/FALSE. The help page is updated accordingly.

+ Fixed an issue with DT[order(…)] optimisation where it's already sorted. 'forder' returns integer(0) for that case. All good now. Thanks Matt.

+ Fix for #5423 - DT[, y := y * eval(parse(text="1*2"))] works fine now without needing to wrap it as y * (eval(…))

+ Implemented FR #5172 - anyDuplicated.data.table method. Test added, NEWS and ?duplicated updated.

+ FR #5205 done - 'duplicated' and 'unique' gain 'fromLast' argument. Added extensive tests and updated NEWS and ?duplicated.

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/datatable@1234 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Minor: Added `anyDuplicated` to 'Value' section in ?duplicated. No changes to code.

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/datatable@1235 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
More fixes for DT[order(…)] issues. Thanks for spotting and for the suggestions Matt. Everything except `na.last` argument should work well now.

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/datatable@1236 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Taking care of the fact that 'forder' is not yet exported. Edge case for DT[order(.)].

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/datatable@1237 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
DT[order(.)] is completely consistent with base's order. Only 'na.last' to be taken care of. Extensive tests added.

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/datatable@1238 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Added anyDuplicated alias to ?duplicated (was a warning in R-forge check).
Fixed a bug when using 'subset' argument to dcast.data.table. Added tests. Dint update NEWS as it's due to changes to dcast in 1.9.3.
Squashed commit:

+ Fixed a bug when using 'subset' argument to dcast.data.table. Added tests. Dint update NEWS as it's due to changes to dcast in 1.9.3.
+ Added anyDuplicated alias to ?duplicated (was a warning in R-forge check).

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/datatable@1239 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
+ Added setNumericRounding, #5369
+ Simplified twiddle()

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/datatable@1240 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Merge branch 'refs/heads/r-forge-git-svn-local'

Conflicts:
	pkg/NEWS
	pkg/inst/tests/tests.Rraw
	pkg/src/init.c
FR #2722 is now implemented. `DT[, c(., lapply(.SD, sum), .), by=grp]` is now optimised. Tests added and news updated.
+ Fixed setNumericRounding(0) and added more tests.  Thanks to James Sams for testing.
+ Added getNumericRounding()

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/datatable@1241 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Don't optimise if `.SD` is present in another form than `lapply(.SD, ..)`. Too many special cases are there. Ex: `DT[, c(.SD, a+.SD, .SD[x>1], .SD[J(.)], lapply(.SD, sum)), by=grp]` - presence of any of the other such .SDs will revert to no optimisation.
Marked various TO DOs and better variable names (minor changes). Updated NEWS to better reflect exactly what cases will be optimised.
Merge branch 'refs/heads/r-forge-git-svn-local'
FR #2722 is now implemented. `DT[, c(., lapply(.SD, sum), .), by=grp]` is now optimised for almost all cases, except really complex cases. Check out NEWS for more info.

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/datatable@1242 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
+ Fixed setNumericRounding(0), more tests added.
+ Added integer64 support in grouping and joins (tests there but switched off until fully works)

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/datatable@1243 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Merge branch 'refs/heads/r-forge-git-svn-local'

Conflicts:
	pkg/inst/tests/tests.Rraw
integer64 grouping and join tests turned on and pass

git-svn-id: svn+ssh://svn.r-forge.r-project.org/svnroot/datatable@1244 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Merge branch 'refs/heads/r-forge-git-svn-local'