This commit fixes bug reported by Patrick Massot.
It happened when using `macro_rules` and `elab_rules` for the same
`SyntaxNodeKind`.
It also fixes missing error messages when there is more than one
elaboration functions and there is `abortTactic` exception.
Remark: this commit also changes the evaluation order. Macros are
now tried before elaboration rules. The motivation is that macros are
already applied before elaboration functions in the term elaborator.
We might also want to replace them with fresh vars to make the hover
completely independent of the context, but this change at least avoids
any hidden information.
Also consistently use binders as reference position for an elided binder type.
Before, type errors were always given extent 1, the length of the
synthetic `_` token.
