Check ob_get_level() at ob_end_* calls where ob wasn't explicitly started
Update getPK() to look for Schema Version 1.1 indexes first
Bump version for 2.2.8-dev
[#9864] Identify compound PK's properly in xPDOQuery::parseConditions()

Add an additional check to make sure the value is a scalar
Fix invalid call to $this->xpdo->log()

in xPDO->getCriteriaType()
Fix xPDO::getInstance() when reusing existing

if getting an existing instance without indicating an $id, calling key(self::$instances) would fail because you cannot pass self::$instances by reference since it is not a variable
Fix xPDO::prepare() sending no driver_options
Fix undefined constant object in xPDO->toCache()
Fix xPDOIterator->next() using void return value
Various documentation corrections
Merge remote-tracking branch 'Flygenring/develop' into develop
Bump version for 2.2.8-pl release
xPDO 2.2.8-pl

Merge branch 'develop'

* develop:
  Bump version for 2.2.8-pl release
  Various documentation corrections
  Fix xPDOIterator->next() using void return value
  Fix undefined constant object in xPDO->toCache()
  Fix xPDO::prepare() sending no driver_options
  Fix xPDO::getInstance() when reusing existing
  Fix invalid call to $this->xpdo->log()
  [#9864] Identify compound PK's properly in xPDOQuery::parseConditions()
  Bump version for 2.2.8-dev
  Update getPK() to look for Schema Version 1.1 indexes first
  Check ob_get_level() at ob_end_* calls where ob wasn't explicitly started