full list of changes below:

- fixed ModelCriteria::clear()
- added ModelCriteria::clear() tests
- refactored query object create()
- added, removed or updated bunch of phpDocs
reduced ModelCriteria::clear() tests
make ModelCriteria::create() changes more backward compatible
fix generated CS of SoftDelete in forceDelete()
Merge pull request #657 from havvg/master

fix generated CS of SoftDelete in forceDelete()
Merge pull request #653 from alanbem/hotfix/query_object_reset

Can't fully reset query objects.
fixed urls to trac tickets propel.phpdb.org/trac/ticket -> trac.propelorm.org/ticket
removed duplicated assertion, refs #653
Add to Criteria support for IN and NOT IN operators in JOIN conditions
e.g. JOIN x ON (x.id = y.x_id AND y.foo IN (42, 51))
Use Criterion always when possible
Using Criterion allows to bind values in statements.
You can't use Criterion only for strings because in this method
you can't distinguish if it is a table name or value provided by user.
Additional assertion to ensure binding params doesn't change actual result
Add test for ModelCriteria to prove it support IN operator in JOIN conditions
Merge pull request #659 from staabm/separate_test

removed duplicated assertion, refs #653
Merge pull request #637 from arvenil/in-operator-in-join-conditions

Bugfix for IN operator in JOIN conditions
only generate findOneBySlug if required
Merge pull request #663 from havvg/feature/sluggable-querymethods

only generate findOneBySlug if required
add an excluded_parent_behavior to concret_inheritance behavior
clean
Merge pull request #664 from mazenovi/master

add an excluded_parent_behavior to concret_inheritance behavior
Fixed #651. Stupid typo.