Add RSSExtension extension

A loadable module version of the Robust Statistics Segmenter module
update RSS commit version
Add RSS Extension
BUG: fix a compilation error on Mac
Merge branch 'add-RSSExtension' of github.com:gaoyi/ExtensionsIndex into add-RSSExtension

Conflicts:
	RSSExtension.s4ext
Merge pull request #439 from gaoyi/add-RSSExtension

Add rss extension - Mac build error should be fixed