Refactor Gen
App.Gen: control number of headlines from CLI

Conflicts:
	src/App/Gen.hs
App.Gen: control prediction context from CLI
App.Gen: add groupnames to cli help
Gen: improve by dropping straight prefixes
Replace scraped.lhs with a simpler script
Merge branch 'loop'
Merge branch 'cli-for-gen'
Merge branch 'ignore-prefix'