some TODOs
Merge branch 'master' of https://github.com/stefanvonderkrone/star-exec-presenter
changed handler `DisplayHtmlProofR` to `DisplayProof` and its argument von `Int` to `Text`
now this handler manages the proofs of solver (html and xml) and the appropriate xsl-stylesheet
Merge branch 'master' of https://github.com/stefanvonderkrone/star-exec-presenter