+ getRversion replaced with behaviour tests
+ various changes to maintain backwards compatibility, highlighted by a few of the 43 dependent packages
+ 2 fixes flagged by ASAN (integer64 overflow in fread and buffer overflow in rbindlist)
+ join from empty character crash fixed
+ key args removed from [.data.table (it failed gems). To revisit.
+ cbind(DF,DT) returns DF (packages depend on that, and seems better anyway). Use data.table(DF,DT) to return a DT.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/datatable@1197 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
v1.9.2 now on CRAN.  Bump to v1.9.3.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/datatable@1198 edb9625f-4e0d-4859-8d74-9fd3b1da38cb