Refactor & clean up

[epost]

• [x] Reformat examples/*.cql.
• [x] Move code in Language to Language.CQL.
• [x] Move code in Parser.hs to Parser/Program.hs.
  • [x] Simplify code.
  • [x] Clarify variable naming.
• [x] Move QuickCheck generator for parsers under test dir tree.
• [x] Tighten imports.
• [ ] Organise test code sensibly.
• [ ] Move dependencies in packages.yaml from dependencies to test dependencies where possible.
• [x] Split off Morphism.hs from Term.hs.
• [x] Split off Collage.hs from Term.hs.
• [x] Split off Presentation.hs from Instance.hs
• [x] Split off Algebra.hs from Instance.hs
• [x] move assembleGens from Instance into Collage
• [x] rename simplifyFix to simplifyTheory in Term.hs
  • [x] rename simplify to simplifyTheoryStep in Term.hs
• [x] Introduce Theory type alias in Term.hs
• [x] Rename findSimplifiable -> findSimplifiableEqs in Term.hs
• [x] Rename simplifyAlg -> A.simplify
• [x] Rename presToCol to IP.toCollage
• [x] Rename schToCol to Schema.toCollage
• [ ] Refactor schToCol
  • [x] modularise uppgrading of EQuations
• [ ] Rename tsToCol to Typeside.toCollage
• [ ] Rename xxxToCol to Xxx.toCollage
• [x] Rename checkSatisfaction -> I.satisfiesSchema
• [x] Rename typecheckPresentation -> IP.typecheck
• [x] Use Carrier type alias in Instance.hs
• [ ] Split off Theory.hs from Term.hs? (Consider making it a submodule of something.)