ignore all .Rproj files using gitignore
use asterisk pattern in .gitignore

This lets us ignore all files whose extensions are specified in the
.gitignore
Delete AC.Rproj

.RProj files should be ignored in the directory for now.
Merge pull request #1 from nancpond/cleanup-gitignore

Cleanup gitignore
Checking in the AC paper from Ji and Gallo
Merge pull request #2 from nancpond/nan

Real-life comparison
Some generated data with negative AC
Merge pull request #3 from nancpond/nan

Nan