do not stop when library() fails
update branch Thu Oct  2 02:29:02 CDT 2014
update branch knitr Thu Oct  2 13:02:26 CDT 2014
update branch knitr Thu Oct  2 14:49:45 CDT 2014
update branch knitr Thu Oct  2 19:41:50 CDT 2014
update branch knitr Thu Oct  2 23:52:25 CDT 2014
update branch knitr Fri Oct  3 02:15:17 CDT 2014
update branch knitr Fri Oct  3 12:36:49 CDT 2014