explicitly set repo, required for Travis-CI
Merge branch 'master' into develop

Conflicts:
	Makefile
Merge remote-tracking branch 'yihui/master' into develop
install tikzDevice
new diff target
install RTikZDevice from GitHub
reinstall devtools from GitHub
cargo cult: use methods library to avoid error message about 'as'
set CRAN repo also for install_github
use fork with NAMESPACE file
quick install of RTikZDevice to avoid building vignettes
more dependencies
count differences
install fonts-freefont-ttf for FreeSans.ttf
ignore generated file
update R and package version info
remove spurious newlines
manually load methods package to avoid error message
TODO: Why is this gone?
package used to be called ttf-freefont just until 12.04; argh...