Remove Integer floor and prefix index from Jaro distance

The variable ``length2`` is an Integer, call to floor returns self.
The variables ``i`` and ``prefix_bonus`` are equally incremented, no need to keep the ``i`` variable.

lib/did_you_mean/jaro_winkler.rb

@@ -8,7 +8,7 @@ def distance(str1, str2)
 
       m          = 0.0
       t          = 0.0
-      range      = (length2 / 2).floor - 1
+      range      = length2 / 2 - 1
       range      = 0 if range < 0
       flags1     = 0
       flags2     = 0
@@ -72,10 +72,8 @@ def distance(str1, str2)
         codepoints2  = str2.codepoints
         prefix_bonus = 0
 
-        i = 0
         str1.each_codepoint do |char1|
-          char1 == codepoints2[i] && i < 4 ? prefix_bonus += 1 : break
-          i += 1
+          char1 == codepoints2[prefix_bonus] && prefix_bonus < 4 ? prefix_bonus += 1 : break
         end
 
         jaro_distance + (prefix_bonus * WEIGHT * (1 - jaro_distance))