Improve console REPL completion

Improve REPL completion. Currently `ImportCompleter` will not work on this example:
```\import Combinatorics.{-caret-}```
Instead default completion will add Fin (instead of BinOp and Factorial).

Also make console completions smarter...

Start by locating ImportCompleter and the console REPL completion entry points, then reproduce the `import Combinatorics.{-caret-}` example. Compare the suggested `Fin` completion with the expected `BinOp` and `Factorial` results. Done means import completion handles this case and the console completion behavior is made smarter as defined by the resulting tests.

Written by the indexing model from the issue text.