Fixed removeStopwords, now preserves case, correctly loads the stopword list, and has better examples.
Pulled latest tutorials.
Sync from RStudio

Merge branch 'dev' of https://github.com/kbenoit/quanteda into dev

Conflicts:
	examples/twitterExample.R
	tutorials/twitter.synctex.gz
	tutorials/twitter/twitter.log
	tutorials/twitter/twitter.pdf
Merge branch 'dev' of https://github.com/kbenoit/quanteda into dev