Imported GNU-R version 66442 from http://svn.r-project.org/R/trunk
DispatchGroup optimization (extracting loop invariant expression). Cleanups - extracting methods.
One more DispatchGroup optimization - extracting updating via S4 slot to a method, avoiding some branches.
Merge branch 'dispatchgroup-optimization-cleanup' of http://www.github.com/kalibera/rexp into dispatchgroup-optimization-cleanup

Conflicts:
	src/include/Rinternals.h