This will allow to unify with types used earlier in the
pipeline (`Scopelang.Ast.typ`).
It seems cleaner! But some areas may warrant a later clean-up, in particular
handling of options and their types in the backends, or possible name conflicts
of structs/enums with built-in types when printing.
Note that there were significant differences between the two printers (see the test diff!). Overall the `dcalc` one seemed newer so that's what I took, with only the required additions from `lcalc` (exceptions, raise and catch)
Handling code should now be reasonably well sorted between `Shared_ast.{Var,Expr,Scope,Program}`
The function parameters (e.g. `make_let_in`) could be removed from the
scope handling functions since now the types are compatible, which
makes them much easier to read.
The AST structures track annotations (e.g., at the moment, source code
position information) in a lot of places. This patch tidies up a bit and
removes some duplication, ensuring a single level of annotation wrapping
at each AST recursion level.
This will be important when adding type information in these
annotations, because there will be consitency constraints to be ensured
and duplication is a likely source of mistakes.
this patch is just a bunch of `sed` commands
```shell
cd compiler
sed -i 's/Pos.marked/Marked.pos/g' *.ml* **/*.ml*
sed -i 's/Pos.unmark/Marked.unmark/g' *.ml* **/*.ml*
sed -i 's/Pos\.get_position/Marked.get_mark/g' *.ml* **/*.ml*
sed -i 's/Pos\.same_pos_as/Marked.same_mark_as/g' *.ml* **/*.ml*
sed -i 's/Pos\.map_under_mark/Marked.map_under_mark/g' *.ml* **/*.ml*
sed -i 's/Pos\.mark/Marked.mark/g' *.ml* **/*.ml*
sed -i 's/Pos\.compare_marked/Marked.compare/g' *.ml* **/*.ml*
```
