eval top level on open paren

I most frequently use ,et to evaluate the top level form, but it would be great if it could be a little bit less picky. When run on the closing paren of a form it works fine, but when run on the opening paren it complains that it isn't in a top level form. This is can be frustrating because it means you can't scroll down the first column evaluating forms in a buffer. Instead you need to scroll down and then over one. Hopefully it would be an easy thing to fix.

Thanks!

-Jeff

Allow sexp extraction with cursor on opening paren

Fixes #71

→ 596d9c6607e7