* added ability user to perform some short tasks right before PubNub client suspension on application entering background execution context
[#70807512]
* changed queue logic to handle client suspension / resume in a bit different way (in perspective of requests)
[#73293212]
* fixed crash because of block/string copy
[#73293212]
* added few data check to prevent crash
[#73293212]
Merge branch 'fix-pt73293212' into feature-73293212-70807512
[#70807512]
Merge remote-tracking branch 'origin/feature-pt70807512' into feature-73293212-70807512

Conflicts:
	iOS/iPadDemoApp/pubnub/Classes/Model/PNDataManager.m
Copy libs.
[#73293212] Fixed issue with rescheduled blocks
* fix related to the crash when wrong associatedObject has been specified for error instance
Add test for bring to foreground mode.
Merge remote-tracking branch 'origin/develop' into feature-73293212-70807512
Copy libs.
[#73733264] * fixed imports inside private classes and library can be added into Swift environment w/o any errors or warnings
Merge branch 'master' into develop
Update version. Copy libs to sample projects.
Update PodSpec.