Improve search results and highlighting

[amake]

Search queries don’t quite work how you might expect: the pattern (string or regexp) is matched against (and highlighting applied to) each parsed token separately. So queries that one might expect to match will not match because the expected hit straddles multiple tokens.

Example: a string query foo/ bar or regexp query foo.*bar will not match the org content

/foo/ bar

because the tokens ['/', 'foo', '/'], 'bar' are each matched separately.