Support for pysqlite
sqlite3 was added in 2.5 and since peewee is 2.5+ compatible, there's really no need.  If someone should want to use the alternate driver they can simply subclass the SqliteAdapter/Database and override as needed.  Thanks for bringing this up, though!

To my knowledge, the sqlite3 module from the stdlib has the same API as the external pysqlite:
http://code.google.com/p/pysqlite

In case the sqlite3 module is absent, peewee could try to use pysqlite instead:

``` python
try:
    import sqlite3
except ImportError:
    try:
        from pysqlite2 import dbapi2 as sqlite3
    except ImportError:
        sqlite3 = None
```
