Provide a strong boost for upper case matches.

This change feels more satisfying for #3263.

This simplifies the code by removing the "CaseMatch" and just providing a boost for upper case. `function` vs. `Function` because of how the prefix match logic works. I'm not sure if there are cases for the full string match logic where we'd prefer case matching even for lower case, but in my random testing (plus the results of the automated tests), I'm happy with how this works...