Add kind information to type declarations in FlatCurry

See merge request !19

Remove higher rank polymorphism extensions for now

See merge request !18

See !19 (comment 8669)
for rationale.

Add Kind information to explicitly bound type variables in FlatCurry

See merge request !15

Include the removal of ExistentialQuantification again.

- 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>

- (WIP) Include information about Layout in SpanInfo
- Add LayoutInfo while parsing, but don't print it on file export (yet)
- Parse QualTypeExprs again
- Add Binary instances for AST (WIP)
- Fix parsing issues with empty where clauses (WIP)
- Do not insert a virtual semicolon when it is followed by a where
- Fixes failure on where-blocks that are immediately after do-blocks with the same indentation
- Add even more binary instances
- Properly add already available test cases
- Use Pretty class from Curry.Base.Pretty (WIP)
- Merge remote-tracking branch 'origin/data-class' into version3
- Fix haddoc comment
- Fix SpanInfos for Idents and where-clauses
- Merge branch 'explicit-layout-info'
- Fix remaining compilation issues
Co-Authored-By: Kai Prott <kai.prott@hotmail.de>

Add functions for generating span previews

See merge request !17

Provide span information in messages

Closes #17

See merge request !16

...instead of from the start to the end column, since those may no
longer be in order in multi-line spans.

This change thus fixes the previews for multi-line spans.

Change msgPos :: Position to msgSpanInfo :: SpanInfo, migrate to the new
span-based messages and add utility functions, e.g. for converting
positions to single-character spans.

Add Kind information to explicitly bound type variables in FlatCurry

See merge request !15

Add support for the `ExplicitForAll` language extension

See merge request !13

Version3

See merge request !12

Add support for higher-rank polymorphism

See merge request !9