Resolve xPDO::parseBindings() error from /e modifier fix

Fixes related errors including xPDO::removeObject() errors
Merge remote-tracking branch 'xpdo/develop' into develop

* xpdo/develop:
  Resolve xPDO::parseBindings() error from /e modifier fix
Fix xPDO->parseBindings bug triggering modDbRegisterMessage errors

Closes modxcms/revolution#785
Closes modxcms/xpdo#27

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

* xpdo/develop:
  Resolve xPDO::parseBindings() error from /e modifier fix