enrich raw with summary data...

...so that diagrams can be drawn directly from it, instead from
export-ready tables.
Still needs calculation of all_revenue of a thing
populate raw data with total revenue of each thing
compute length of data set more elegantly
flattr_plot omits outliers beyond 5x of mean
corrected some comments
resolved syncing-related conflict
local changes after sync conflict resolution
Merge remote-tracking branch 'origin/develop' into develop

Conflicts:
	summarize-flattr-reports.R
resolved manually
removed height_modifier in favor of N_things
Merge branch 'simpler-sizesing' into develop
clean-up

- 2 spaces in front of each + in plotting code to increase visibility
- auto-removed trailing white-spaces
- clarified some comments
added proper locale (fixed +5) & functionalised plot preview
aggregated axis labelling into single line per plot
easier color recognition in flattr_plot legend
Merge branch 'develop'