empathy: Pre-group words according to common patterns

empathy: Pre-group words according to common patterns

Specifically, the following will be considered identical and
pre-grouped:

	<word> = <word>s
        <word> = a <word>
        <word> = an <word>
        <word> = the <word>

Unlike the server-side canonicalization of case differences, which are
not visible, the above matching words are all still made available to
the player and simply pre-grouped. So, the player can decide whether
to leave them grouped or to separate them back out.