workaround side-effects in spatstat

git-svn-id: https://svn.r-project.org/R/trunk@62807 00db46b3-68df-0310-9c12-caf00c1e9a41
another try

git-svn-id: https://svn.r-project.org/R/trunk@62808 00db46b3-68df-0310-9c12-caf00c1e9a41
Allow a user to request running \dontrun sections in example().

git-svn-id: https://svn.r-project.org/R/trunk@62809 00db46b3-68df-0310-9c12-caf00c1e9a41
Skip clang -Wsometimes-uninitialized compilation warnings by default.

git-svn-id: https://svn.r-project.org/R/trunk@62811 00db46b3-68df-0310-9c12-caf00c1e9a41