feature: sort by longest exact match in immersion kit & massif

[m-edlund]

Makes a slight improvement to sorting in immersion kit. For words where there are a lot of unfitting results returned by immersion kit, this should float the best ones to the top.

ImmersionKit Example:

Compound verbs such as 聞き入る

Before	After

Rare kanji versions of common words such as 成る

Before	After

Massif Example:

Compound verbs such as 聞き入る

Before	After

Rare kanji versions of common words such as 聴き入る

Before	After