Fixed Memory leaking issue #83

[farshadmb]

Hi Dear
@msaps I found the leaking object which holds pageboyViewController and doesn't allow to deallocate pageboyViewController after pop or dismiss

• Fixed strong reference in CADisplayLink
• Clear viewControllers content after deallocated
• Fixed animation property strong reference

issue reference : MemoryLeak

[codecov]

Codecov Report

Merging #84 into develop will decrease coverage by 1.72%.
The diff coverage is 0%.

@@             Coverage Diff             @@
##           develop      #84      +/-   ##
===========================================
- Coverage    69.26%   67.54%   -1.73%     
===========================================
  Files           20       20              
  Lines         1012     1026      +14     
===========================================
- Hits           701      693       -8     
- Misses         311      333      +22

Impacted Files	Coverage Δ
...tensions/PageboyViewController+Transitioning.swift	10.44% <0%> (-13.29%)	⬇️
...ources/Pageboy/Utilities/TransitionOperation.swift	0% <0%> (ø)	⬆️
Sources/Pageboy/PageboyViewController.swift	74.24% <0%> (-1.92%)	⬇️

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[farshadmb]

@msaps What was that 👍 🙃

[msaps]

@farshadmb just changed the base branch to develop and updated with the latest changes 😄