- Merge branch 'fix-warnings' into 'master'
  Fix some compiler warnings in the syntax modules
  See merge request !10
- Merge branch 'remove-exist-quant' into 'master'
  Remove support for existential quantified type variables in data type declarations
  See merge request !11


- Update Pretty and Binary instances for ConstrDecl

Co-authored-by: Finn Teegen <fte@informatik.uni-kiel.de>