Merge pull request cocos#6088 from 2youyou2/v2.3.0-delete-effect

fixed error when effect was deleted

fixed calculateDeltaTime error

Fixed a problem that the Letter Font showed a white border. cocos#5551 (

cocos#5903)

Fix a memory leap of RichText. (cocos#5906)

adjust type of cc.ParticleSystem.file (cocos#5819)

adjust type of cc.ParticleSystem.file (cocos#5819)

Merge pull request cocos#5799 from caryliu1999/v2.2.1-release-RUNTIME

Modify _BASELINE_RATIO on runtime.