Improve fuzzy matching

This is another series of small fuzzy improvements
- Sequential bonuses starting from a separator match are slightly
adjusted so that they are not too far behind a bonus resulting from
a match at the start of string. This helps in bumping up a result
if the file was open for e.g.,

- Introduction of gap penalty. Gap penalty is applied in two ways.
1. If the gap is between two separators, the penalty is higher and
cancels out the bonus if the gap is >= 9 chars
2. For a normal gap, penalty is -1 * gap length
This helps in making the algorithm more "fuzzy" and less "acronym-y".

Sequential bonuses starting randomly are increased with each subsequent
matching letter. On a mismatch the bonus value is reset to 10. Applying
this bonus correctly is crucial as otherwise it can render the
recursive best matching useless.