Allow recursive xPDOObject::remove() beyond one level

Still prevents circular dependency problems without preventing proper recursive functionality by keeping track of specific objects being removed from each class by primary key, rather than just excluding all objects by alias or class of already processed relations

Addresses modxcms/xpdo#23 and should resolve modxcms/revolution#11453
Proposal for silent failure validation
Update taking care or comment + replicated to other vehicles types
Have xPDOVehicle validators fail silently unless verbose enabled

Merge remote-tracking branch 'origin/pr/26' into develop

* origin/pr/26:
  Update taking care or comment + replicated to other vehicles types
  Proposal for silent failure validation
Revert silent validation feature for now
Update copyright date
Bump version for 2.3.0-pl release
xPDO 2.3.0-pl

Merge branch 'develop'

* develop:
  Bump version for 2.3.0-pl release
  Update copyright date
  Revert silent validation feature for now
  Update taking care or comment + replicated to other vehicles types
  Proposal for silent failure validation
  Allow recursive xPDOObject::remove() beyond one level
  Fix notice introduce in previous commit
  Remove deprecated xPDO::getMicroTime() method
  Fix bug with conditions referencing keys outside xPDOQuery::$_class
  Reject xPDOQuery conditions with SQL injection attempts
  Resolve xPDO::parseBindings() error from /e modifier fix
  Fix xPDO::getCount() to work with queries containing group by
  Replace reflection of PHP_SELF with SCRIPT_NAME in xPDO::log()
  Fix for deprecated preg_replace
  Add changelog entry
  Add dependency metadata/methods to xPDOTransport
  Bump version for 2.3.0-alpha development
  Disable phpdoc generation in build for now
  Update code docs, fix invalid constant
  Schema option callback="(class::)method" added to xPDOObject::set()
xPDO Core 2.3.0-pl

Merge remote-tracking branch 'xpdo/master'

* xpdo/master:
  Bump version for 2.3.0-pl release
  Update copyright date
  Revert silent validation feature for now
  Update taking care or comment + replicated to other vehicles types
  Proposal for silent failure validation
  Allow recursive xPDOObject::remove() beyond one level
  Fix notice introduce in previous commit
  Remove deprecated xPDO::getMicroTime() method
  Fix bug with conditions referencing keys outside xPDOQuery::$_class
  Reject xPDOQuery conditions with SQL injection attempts
  Resolve xPDO::parseBindings() error from /e modifier fix
  Fix xPDO::getCount() to work with queries containing group by
  Replace reflection of PHP_SELF with SCRIPT_NAME in xPDO::log()
  Fix for deprecated preg_replace
  Add changelog entry
  Add dependency metadata/methods to xPDOTransport
  Bump version for 2.3.0-alpha development
  Disable phpdoc generation in build for now
  Update code docs, fix invalid constant
  Schema option callback="(class::)method" added to xPDOObject::set()
Update to xPDO 2.3.0-pl

Merge remote-tracking branch 'xpdo/master' into develop

* xpdo/master:
  Bump version for 2.3.0-pl release
  Update copyright date
  Revert silent validation feature for now
  Update taking care or comment + replicated to other vehicles types
  Proposal for silent failure validation
  Allow recursive xPDOObject::remove() beyond one level

Conflicts:
	core/xpdo/changelog.txt