make script executable via Rscript: `Rscript path/to/script.r path/to/flattr-revenue-YYYYMM.csv`
summarize by domain (e.g. github.com, flattr.com, twitter.com, alpha.app.net, shownot.es, ...)
Merge pull request #8 from SimonWaldherr/group-by-domain

summarize by domain (e.g. github.com, flattr.com, twitter.com, alpha.app...
Merge pull request #9 from SimonWaldherr/cli

make script executable via Rscript: `Rscript path/to/script.r path/to/fl...
grouped plot-related code to plot code blocks