Querybuilder rewrite

Targeted version: 2.0
Core dev responsible: (none yet)
Repo: fuel/query-builder

Changes agreed upon

The compilation should go into the sql engine driver instead of in the QB
PDO will be the "default" driver, with mysql & mysqli drivers included for legacy support
The base PDO driver will have specialized extensions for mySQL, SQLite and PostgreSQL
Other extensions can be developed if there is enough support for it (both dev's and testers)

Let's look into merging the DBUtil class into the drivers of the Query Builder (Jelmer)
Define generic syntax for DBUtil so it becomes more portable (Harro)
Solve the issue of passing DB objects to View when encoding is enabled (Harro)
Base the connection part around PDO (Jelmer)
Base the query builder syntax around mySQL (Jelmer)
Support no-sql databases MongoDB and CouchDB (Frank)
Separate the query builder into a Query Collector and Query Compiler to support no-sql databases and dialect specific sql. (Frank)
Replace current query return value (insert id, affected rows) by a method on the result object, requiring the tables primary keys as parameter. That would provide all drivers to possibility to return the correct values. (Harro)
All Database classes should be extendable (currently the are loaded hard-coded from \Fuel\Core). (Harro)