This is still experimental, but it implements identifier support in auto
tactics "in the obvious way". It also converts `quoteAutoTactic` to
generate Expr directly instead of going via syntax (this doesn't have
any effect other than increasing compile cost AFAICT).
The current `ToExpr Int` instance produces `@Int.ofNat (@OfNat.ofNat Nat
i ...)` for nonnegative `i` and `@Int.negSucc (@OfNat.ofNat Nat (-i+1)
...)` for negative `i`.
However it should be producing `@OfNat.ofNat Int i ...` for nonnegative
`i`, and `@Neg.neg ... (@OfNat.ofNat Int (-i) ...)` for negative `i`.
This is pretty big PR that upstreams all of Std.Data.Int.Init in one go.
So far lemmas have seen minimal changes needed to adapt to Lean core
environment.
---------
Co-authored-by: Scott Morrison <scott.morrison@gmail.com>
