This allows to support pyright which doesn't support sub-typing of conditional types.
See https://github.com/microsoft/pyright/issues/2047.

Not a breaking change since no version has been released.

BREAKING CHANGE: this shouldn't affect projects since updating rql will automacally install the new dependency.

Without this, we have an error if we have aggregate functions indise other
function.

related: cubicweb#242

update undo_manager property, type:
  self._undo_manager as SelectionManager
and fix:
  rql/stmts.py:424: error: Cannot determine type of "_undo_manager" [has-type]

rewrite the undo_manager function and make sure it always returns a SelectionManager

- remove even more useless comments
- remove even more useless casts

if we want to use it as 2nd arg to the property function:
- set_limit method should explicitly return None
- remove useless comments
- remove now useless type:ignore comments

This fix mypy error:
Argument 2 to "property"
 has incompatible type "Callable[[rql.stmts.Union, Any], Optional[rql.stmts.Union]]"
 expected "Optional[Callable[[Any, Any], None]]"

- annotate schema as ISchema
- remove useless comments
- remove useless cast
- remove now useless type:ignore comments

- `visit_insert` method should only accept rql.stmts.Insert type nodes
- `visit_delete` should only accept rql.stmts.Delete type nodes

- improve type aliases, Select is not a statement
- pick better names for type aliases

The `_visit` method receive a node as first parameter.
Annotate `node`:
- either as a union of all 18 possible node types
- or just type node as BaseNode (picked solution)

There was an unused protocol definition sleeping within the rql/interfaces.py module.
This protocol (ISchema) perfectly represent what a schema should be.
Let's use it to annotate the schema attribute within the RQLHelper class

Within rql/analyze.py:
----------------------
  add (line 403):
      if self.uid_func:
  and fix:
      error: "None" not callable  [misc]

  add (line 548):
      assert self.uid_func_mapping is not None
  and fix:
      Unsupported right operand type for in ("Optional[Dict[Any, Any]]")

  change (line 615):
      etypes = frozenset(t for t in self._nonfinal_domain if t not in etypes)
  to:
      etypes = set(t for t in self._nonfinal_domain if t not in etypes)
  and fix:
      Incompatible types in assignment (expression has type "FrozenSet[str]", variable has type "Set[Any]")


Within rql/interfaces.py:
-------------------------

Update ISchema protocol definition:
    add:
        def __contains__():
    and fix:
         error: Unsupported right operand type for in ("ISchema")  [operator]

    add:
        def rschema(self, rtype: Any):
    and fix:
        "ISchema" has no attribute "rschema"  [attr-defined]

    add:
        def eschema(self, etype: Any):
    and fix:
        "ISchema" has no attribute "eschema"  [attr-defined]


See RQL's issue: #15

To easily build the wheel using `build_wheel.sh` shell script

In order to upload a RQL build using the (faster) gecode library.