Add soundex support to MySQL (and others)

[dacort <django@…>]

I needed to use MySQL sounds like support in an app recently and found it to be seemingly easy to add support for this. Not sure what the policy is about database-specific calls, but at least both postgres, sqlite, and oracle all appear to support some form of soundex.

​http://www.postgresql.org/docs/8.3/static/fuzzystrmatch.html
​http://www.sqlite.org/lang_corefunc.html
​http://www.techonthenet.com/oracle/functions/soundex.php

I've attached my changes for MySQL.

[dacort <django@…>]

MySQL "sounds like" (soundex) support

[Malcolm Tredinnick]

Not really worth it. Soundex support has enough collisions that it's often preferable to use other, similar algorithms. So then it becomes a question of which versions to include. Since adding extra lookup types is actually possible by subclassing the Query class (django.contrib.gis already does this), no modifications to core should be needed for this.