fix compact function: also remove non null members with length 0
fix authors section on index page. In case of multiple authors in authors@r, the Authors section title was duplicated with empty content. Added a str_person function to properly display person objects.
{{{title}}} instead of {{title}}. no html escape for titles with \code tags.
fix inside-r links to r builtin packages
fix Value section and parse_descriptions. "Writing R extensions" manual says: "Note that \value is implicitly a \describe environment."
change plot size to 540x400: better for par(mfrow=c(2,2))
keep only high level plots. added slightly modified knitr functions: merge_low_plot, digest_plot, is_low_change
update documentation
Merge pull request #69 from adrtod/master

Several fixes and improvements
Merge remote-tracking branch 'upstream/master'

Conflicts:
	R/package.r
	inst/templates/content-index.html