resolver quickfixes

[cdstanford]

@lzoghbi take a look at the function resolve::resolve_core -- I've put in two temporary fixes for the minor issues we discussed, to get the tests passing.

• s.add(1) moves the column one over for some cases where a whitespace token wasn't resolved as expected
• result.replace_empty_idents() replaces all instances of :::: with ::

Please go ahead and remove these lines when resolved!

    fn resolve_core(&self, i: &syn::Ident) -> Result<CanonicalPath> {
        let mut s = SrcLoc::from_span(self.filepath, i);
        // TODO Lydia remove
        s.add1();
        let i = Ident::from_syn(i);
        let mut result = self.resolver.resolve_ident(s, i)?;
        // TODO Lydia remove
        result.replace_empty_idents();
        Ok(result)
    }