Version to 2.6.0
Install png library for R-2.15.1_bioc-2.11
Merge pull request #12 from ilarischeinin/master

Miscellaneous copy number updates
Merge branch 'master' of https://github.com/chipster/chipster.git
Updated TopHat2 texts and fixed a bug.
Merge branch 'master' of https://github.com/chipster/chipster.git
get rid of Mac DS_Store clutter
improved SADL documentation and cleaned for a bit
Stat-two-groups.R fix from Oliver