AK/FuzzyMatch: Use a first letter bonus of 15 rather than 20

This matches the value used in the original `lib_fts` implementation
of the algorithm.

Author: tcl3

AK/FuzzyMatch.cpp

@@ -17,7 +17,7 @@ static constexpr int const MAX_MATCHES = 256;
 static constexpr int const SEQUENTIAL_BONUS = 15;            // bonus for adjacent matches (needle: 'ca', haystack: 'cat')
 static constexpr int const SEPARATOR_BONUS = 30;             // bonus if match occurs after a separator ('_' or ' ')
 static constexpr int const CAMEL_BONUS = 30;                 // bonus if match is uppercase and prev is lower (needle: 'myF' haystack: '/path/to/myFile.txt')
-static constexpr int const FIRST_LETTER_BONUS = 20;          // bonus if the first letter is matched (needle: 'c' haystack: 'cat')
+static constexpr int const FIRST_LETTER_BONUS = 15;          // bonus if the first letter is matched (needle: 'c' haystack: 'cat')
 static constexpr int const LEADING_LETTER_PENALTY = -5;      // penalty applied for every letter in str before the first match
 static constexpr int const MAX_LEADING_LETTER_PENALTY = -15; // maximum penalty for leading letters
 static constexpr int const UNMATCHED_LETTER_PENALTY = -1;    // penalty for every letter that doesn't matter